JP6782106B2 - Reformer - Google Patents

Description

The techniques disclosed herein relate to reformers.

A reformer is known that produces a reformed gas containing carbon monoxide and hydrogen from a fuel gas containing a hydrocarbon (for example, methane). The reformer is called a technique (GTL (Gas to Liquid)) for producing a liquid hydrocarbon fuel, for example, in order to obtain hydrogen to be supplied to a fuel cell, or by further converting hydrogen and carbon monoxide into hydrocarbons. ) Is used for.

One modification techniques of hydrocarbons, there is a hydrocarbon and reaction with water _{(C n H m + nH 2} O → nCO + (n + m / 2) H 2) steam reforming utilizing. Steam reforming is widely used because it has the advantage that the reaction is stable and easy to proceed. However, the steam reforming reaction is an endothermic reaction, and there is a problem that the efficiency is low because the reforming apparatus needs to be heated in order for the reaction to proceed.

One other modification techniques of hydrocarbons, there is a partial oxidation reforming reaction _{(C n H m + (n} / 2) O 2 → nCO + (m / 2) H 2) Use partial oxidation reforming the .. Since the partial oxidation reforming reaction is an exothermic reaction, it is not necessary to heat the reforming apparatus. However, when air containing oxygen is supplied to the reformer for partial oxidation reforming, energy is required to heat the nitrogen contained in the air to the operating temperature of the reformer, and the efficiency is reduced accordingly. There is a problem of becoming.

Conventionally, there is known a technique of selectively extracting oxygen from air using an oxygen permeable membrane and utilizing the extracted oxygen for partial oxidation modification (see, for example, Patent Document 1). The oxygen permeable film has oxide ion conductivity and electron conductivity or hole conductivity, and drives the oxygen partial pressure difference between the first space and the second space separated by the oxygen permeable film. It is a film that allows oxygen to permeate from the first space to the second space. In a reformer provided with an oxygen permeable film, when air is supplied to the air chamber as the first space and fuel gas containing hydrocarbons is supplied to the fuel chamber as the second space, the air supplied to the air chamber is supplied. The oxygen inside penetrates through the oxygen permeable film and enters the fuel chamber, where a partial oxidation reforming reaction between hydrocarbons and oxygen occurs, which reforms the hydrocarbons. A reformer provided with such an oxygen permeable membrane does not require energy for heating nitrogen, so that high efficiency can be realized.

Special Table 2001-518014

The amount of oxygen that permeates the oxygen permeable membrane changes according to the difference in oxygen partial pressure between the two spaces (air chamber and fuel chamber) separated by the oxygen permeable membrane. In the reforming apparatus provided with the conventional oxygen permeable membrane, the gas composition changes due to the partial oxidation reforming reaction occurring in the fuel chamber, so that the oxygen partial pressure may differ at each position in the fuel chamber. For example, in the part near the gas outlet side in the fuel chamber, the oxygen partial pressure becomes higher due to the progress of hydrocarbon reformation as compared with the part near the gas inlet side, and as a result, the air chamber The difference in oxygen partial pressure between the two becomes smaller, and the amount of oxygen that permeates the oxygen permeable film decreases. As described above, in the reforming apparatus provided with the oxygen permeable membrane, it is difficult to control the amount of oxygen permeated because the amount of oxygen permeating through the oxygen permeable membrane changes according to the difference in oxygen partial pressure. When the amount of oxygen permeating through the oxygen permeable membrane changes, the amount of partial oxidation reforming reaction in the fuel chamber changes, and as a result, the composition of the reformed gas produced also changes. Therefore, in the conventional reformer provided with the oxygen permeable membrane, there is room for improvement in terms of stabilizing the composition of the reformed gas.

This specification discloses a technique capable of solving the above-mentioned problems.

The technique disclosed in the present specification can be realized, for example, in the following forms.

(1) The reformer disclosed in the present specification utilizes a partial oxidation reforming reaction between hydrocarbons and oxygen to convert a reforming gas containing carbon monoxide and hydrogen from a fuel gas containing hydrocarbons. In the reformer to be generated, it has oxide ion conductivity and electron conductivity or hole conductivity, and is arranged between the first space and the second space, and the first space and the first space. An oxygen permeable film that allows oxygen to permeate from the first space to the second space and the fuel gas are supplied to the second space using the difference in oxygen partial pressure between the second space as a driving force. The second, so that the oxygen partial pressure of the fuel gas supply unit and the reformed gas discharged from the second space is within a predetermined range of the lower limit value Pmin or more and the upper limit value Pmax or less. A control unit for controlling the reaction amount of the partial oxidation reforming reaction in the space is provided. According to this reformer, the amount of hydrocarbons contained in the reforming gas is reduced as the oxygen partial pressure of the reforming gas becomes excessively low by simple control based on the oxygen partial pressure of the reforming gas. While suppressing the increase and the decrease in the efficiency of the reformer, it is possible to suppress the poor composition of the reformed gas due to the excessively high oxygen partial pressure of the reformed gas. it can. Therefore, according to this reformer, the composition of the reformed gas is stably contained with hydrogen and carbon monoxide while suppressing the decrease in efficiency by suppressing the amount of hydrocarbons contained in the reformed gas. A good composition with a high ratio can be obtained.

(2) In the reformer, the upper limit value Pmax has a hydrogen selectivity (%) which is a ratio of the volume ratio of hydrogen to the total of the volume ratio of hydrogen in the reforming gas and the volume ratio of water in advance. It is the ratio of the volume ratio of carbon monoxide to the total of the volume ratio of carbon monoxide and the volume ratio of carbon dioxide in the reformed gas and the first condition that the value is equal to or higher than the set first reference value. The configuration may be a value set so as to satisfy at least one of the second condition that the carbon monoxide selectivity (%) becomes equal to or higher than the preset second reference value. According to this reformer, the composition of the reforming gas can be stably set to a good composition in which at least one of hydrogen selectivity and carbon monoxide selectivity is high.

(3) In the reformer, the first reference value may be 95 (%). According to this reformer, the composition of the reforming gas can be stably made into a good composition having a very high hydrogen selectivity of 95 (%) or more.

(4) In the reformer, the second reference value may be 96 (%). According to this reformer, the composition of the reforming gas can be stably made into a good composition having a very high carbon monoxide selectivity of 96 (%) or more.

(5) In the reformer, the lower limit value Pmin is the amount of the hydrocarbon input and the amount of the hydrocarbon contained in the reformed gas with respect to the amount of the hydrocarbon input which is the amount of the hydrocarbon contained in the fuel gas. It is a value set so as to satisfy the third condition that the hydrocarbon conversion rate (%), which is the ratio of the hydrocarbon consumption amount which is the difference between the above and the above, is equal to or higher than the preset third reference value. It may be configured. According to this reformer, the hydrocarbon conversion rate can be stably increased to improve the efficiency.

(6) In the reformer, the third reference value may be 75 (%). According to this reformer, it is possible to realize a reformer having a stable hydrocarbon conversion rate of 75 (%) or more and very high efficiency.

(7) In the reformer, the control unit controls the amount of the fuel gas supplied to the second space by the fuel gas supply unit, thereby performing a partial oxidation reforming reaction in the second space. It may be configured to control the reaction amount of. According to this reformer, the reaction amount of the partial oxidation reforming reaction in the second space can be controlled by simple control, and the composition of the reforming gas can be stably controlled while suppressing a decrease in efficiency. It can have a good composition.

(8) In the reformer, the lower limit value Pmin is 1 × ^10-23 (atm) at 1000 ° C., and the upper limit value Pmax is 1 × 10 ^-17 (atm) at 1000 ° C. May be good. According to this reformer, the oxygen partial pressure of the reforming gas discharged from the second space is within the range of 1 × 10 ^-23 (atm) or more and 1 × 10 ^-17 (atm) or less. As described above, by controlling the reaction amount of the partial oxidation reforming reaction in the second space, the amount of hydrocarbons contained in the reforming gas is suppressed, thereby suppressing the decrease in efficiency, and the reforming gas. The composition can be stably set to a good composition having a high content ratio of hydrogen and carbon monoxide.

(9) In the reformer, the lower limit value Pmin is 1 × ^10-22 (atm) at 1000 ° C., and the upper limit value Pmax is 1 × 10 ^-19 (atm) at 1000 ° C. May be good. According to this reformer, the oxygen partial pressure of the reforming gas discharged from the second space is within the range of 1 × ^10-22 (atm) or more and 1 × ^10-19 (atm) or less. As described above, by controlling the reaction amount of the partial oxidation reforming reaction in the second space, the amount of hydrocarbons contained in the reformed gas is suppressed, so that the decrease in efficiency is effectively suppressed, and the reforming is performed. The composition of the quality gas can be stably adjusted to a good composition having a very high content ratio of hydrogen and carbon monoxide.

(10) In the reformer, the volume ratio (%) of methane to the total hydrocarbon in the fuel gas may be 50 (%) or more. According to this reformer, using such a fuel gas, partial oxidation reforming in the second space is performed so that the oxygen partial pressure of the reforming gas discharged from the second space is within the above range. By controlling the reaction amount of the reaction, the amount of hydrocarbons contained in the reformed gas is suppressed to suppress the decrease in efficiency, and the composition of the reformed gas is stably contained with hydrogen and carbon monoxide. A good composition with a high ratio can be obtained.

(11) The reforming apparatus may further include an oxygen sensor that measures the oxygen partial pressure of the reforming gas discharged from the second space. According to this reformer, the oxygen partial pressure of the reforming gas can be measured by a simple means.

(12) In the reforming apparatus, the oxygen sensor may be configured to measure the oxygen partial pressure of the reforming gas based on the electromotive force generated in the oxide ion conductor zirconia. According to this reformer, the oxygen partial pressure of the reforming gas can be measured accurately by a simple means.

(13) In the reformer, the control unit makes the total volume ratio (%) of hydrogen, carbon monoxide, and hydrocarbon in the reforming gas 95 (%) or more. The configuration may be such that the reaction amount of the partial oxidation reforming reaction in the second space is controlled. According to this reformer, the composition of the reforming gas can be stably made into a good composition having a low content ratio of water and carbon dioxide.

(14) In the reformer, in the control unit, the ratio of the volume ratio (%) of hydrogen to the volume ratio (%) of carbon monoxide in the reformed gas is 1.9 or more and 2.1 or less. The reaction amount of the partial oxidation reforming reaction in the second space may be controlled so as to be. According to this reformer, the composition of the reforming gas is stably substantially the same as the hydrogen-carbon monoxide ratio of the raw material gas required for saturated hydrocarbons synthesized in the Fischer-Tropsch reaction process, for example. be able to.

(15) In the reformer, the hydrocarbon in the fuel gas may be methane. According to this reformer, partial oxidation reforming in the second space is performed by using a fuel gas containing methane so that the oxygen partial pressure of the reforming gas discharged from the second space is within the above range. By controlling the reaction amount of the reaction, the amount of hydrocarbons contained in the reformed gas is suppressed to suppress the decrease in efficiency, and the composition of the reformed gas is stably contained with hydrogen and carbon monoxide. A good composition with a high ratio can be obtained.

The technique disclosed in the present specification can be realized in various forms, for example, a reformer, a control method of the reformer, and the like.

It is explanatory drawing which shows schematic structure of the reformer 10 of this embodiment. It is explanatory drawing which shows the detailed structure of the oxygen permeation membrane structure 110. It is explanatory drawing which shows the detailed structure of the oxygen permeation membrane structure 110. It is a flowchart which shows the flow of fuel flow rate control of a reformer 10. It is explanatory drawing which shows schematic structure of the reformer 300 for evaluation. It is explanatory drawing which shows the performance evaluation result.

A. Embodiment:
A-1. Device configuration:
FIG. 1 is an explanatory diagram schematically showing the configuration of the reformer 10 of the present embodiment. FIG. 1 shows XYZ axes that are orthogonal to each other to specify the direction. In the present specification, for convenience, the Z-axis positive direction is referred to as an upward direction, and the Z-axis negative direction is referred to as a downward direction. The same applies to FIGS. 2 and later.

The reformer 10 is a device that generates a reformed gas RG containing carbon monoxide and hydrogen from a fuel gas FG containing hydrocarbons. The reforming device 10 includes a fuel gas supply unit 210, a fuel gas supply pipe 220, a reaction unit 100, a reforming gas discharge pipe 230, an oxygen sensor 240, and a control unit 250.

The fuel gas supply unit 210 is a device for supplying the fuel gas FG toward the reaction unit 100. The fuel gas supply unit 210 includes a gas source 211 and a flow rate adjusting unit 212. The gas source 211 is composed of, for example, a gas cylinder or a gas tank for storing the fuel gas FG, a connecting flow path connected to a fuel line to which the fuel gas FG is supplied, and the like. Further, the flow rate adjusting unit 212 is composed of, for example, a flow rate adjusting valve, and adjusts the flow rate of the fuel gas FG supplied from the gas source 211. The fuel gas FG supplied by the fuel gas supply unit 210 contains hydrocarbons such as methane, ethane, propane, and butane, for example. The fuel gas FG may contain one type of hydrocarbon or may contain a plurality of types of hydrocarbons. Further, the fuel gas FG may contain a gas other than hydrocarbon (for example, carbon dioxide).

The fuel gas supply pipe 220 is a pipe that connects the fuel gas supply unit 210 and the reaction unit 100, and is connected to one end of the reaction unit 100. The reformed gas discharge pipe 230 is a pipe for taking out the reformed gas RG generated in the reaction unit 100, and is connected to the other end of the reaction unit 100.

The reaction unit 100 is a portion that causes a reforming reaction for reforming the fuel gas FG. The reaction unit 100 includes an oxygen permeable membrane structure 110, a supply side connection pipe 121, a discharge side connection pipe 122, and a storage pipe 130.

The accommodating tube 130 is a member having a substantially cylindrical shape, and is composed of, for example, a glass tube. The oxygen permeable membrane structure 110 is housed in the internal space of the storage pipe 130. The outer peripheral side portion of the oxygen permeable membrane structure 110 in the internal space of the accommodation pipe 130 constitutes the air chamber S1. Air (AIR) is supplied to the air chamber S1 by, for example, a blower (not shown). The air chamber S1 corresponds to the first space in the claims.

The oxygen permeable membrane structure 110 is a member having a substantially cylindrical shape. The space inside the oxygen permeable membrane structure 110 constitutes the fuel chamber S2. The configuration of the oxygen permeable membrane structure 110 will be described in detail later. The fuel chamber S2 corresponds to the second space in the claims.

The supply side connection pipe 121 is connected to one end of the oxygen permeable film structure 110, and the fuel gas FG supplied from the fuel gas supply unit 210 via the fuel gas supply pipe 220 is introduced into the oxygen permeable film structure. It leads to the fuel chamber S2 in the body 110. The discharge side connection pipe 122 is connected to the other end of the oxygen permeable membrane structure 110, and the reformed gas RG discharged from the fuel chamber S2 in the oxygen permeable membrane structure 110 is discharged into the reformed gas discharge pipe. Lead to 230. The supply side connection pipe 121 and the discharge side connection pipe 122 are made of, for example, zirconia.

2 and 3 are explanatory views showing a detailed configuration of the oxygen permeable membrane structure 110. FIG. 2 shows the YZ cross-sectional structure of the oxygen permeable membrane structure 110 at the position II-II in FIG. 1, and FIG. 3 shows the oxygen permeable membrane structure 110 at the position III-III in FIG. The XZ cross-sectional structure of is shown. As described above, the oxygen permeable membrane structure 110 is a member having a substantially cylindrical shape. As shown in FIGS. 2 and 3, the oxygen permeable membrane structure 110 is composed of a support 114, a fuel electrode 112, an oxygen permeable membrane 111, and an air electrode 113. The support 114 is arranged on the innermost peripheral side (the side facing the fuel chamber S2) of the oxygen permeable membrane structure 110, and the fuel is sequentially directed toward the outer peripheral side (the side facing the air chamber S1) from there. The pole 112, the oxygen permeable membrane 111, and the air pole 113 are laminated.

The support 114 is a porous, substantially cylindrical member, and supports other layers (fuel electrode 112, oxygen permeable membrane 111, air electrode 113) constituting the oxygen permeable membrane 111. The support 114 is formed of, for example, stabilized zirconia or the like.

The air electrode 113 is a porous substantially cylindrical member, and functions as a catalyst layer that promotes a reaction (1 / 2O ₂ + 2e ⁻ → O ^2- ) for ionizing oxygen in the air supplied to the air chamber S1. .. The air electrode 113 is formed of, for example, a composite oxide such as La _0.8 Sr _0.2 MnO ₃ or La _0.8 Sr _0.2 CrO ₃ .

The oxygen permeable membrane 111 is a gas-impermeable, substantially cylindrical membrane having oxide ion conductivity and electron conductivity or hole conductivity. In the following description, electron conductivity and hole conductivity are collectively referred to as electrical conductivity. The oxygen permeable film 111 uses the oxygen partial pressure difference between the air chamber S1 and the fuel chamber S2 separated by the oxygen permeable film 111 as a driving force to drive the air chamber S1 on the high oxygen partial pressure side to the fuel chamber S2 on the low oxygen partial pressure side. Selectively permeates oxygen into. The oxygen permeable membrane 111 is made of, for example, a mixture of a substance having oxide ion conductivity (hereinafter referred to as “oxide ion conductor”) and a substance having electrical conductivity (hereinafter referred to as “electric conductor”). It is formed. The oxygen permeable membrane 111 may be formed of a substance having both oxide ion conductivity and electrical conductivity (hereinafter, referred to as “mixed conductor”). Further, the oxygen permeable membrane 111 may be formed by a mixture of at least one of an oxide ion conductor and an electric conductor and a mixed conductor.

As the oxide ion conductor, for example, stabilized zirconia, partially stabilized zirconia, a ceria-based solid solution, or the like can be used. As the electric conductor, for example, an oxide having a perovskite structure, a ferrite having a spinel-type crystal structure, a metal material such as a noble metal, or the like can be used. Mixing The conductor additive, for example, in LaGaO ₃ type compounds, LSGF based oxide having a perovskite structure with the addition of Fe to the Ga site with the addition of Sr to La sites, the SrCoO ₃ based compound, a Ba to Sr site A BSCF-based oxide having a perovskite structure, an oxide having a layered perovskite structure, an oxide having a fluorite-type structure, an oxide having an oxyapatite structure, an oxide having a merylite structure, etc. Can be used.

The fuel electrode 112 is a porous substantially cylindrical member, and has permeated the hydrocarbons in the fuel gas FG supplied from the fuel chamber S2 through the support 114 which is the porous member and the oxygen permeable film 111. It functions as a catalyst layer that promotes the partial oxidation modification reaction (C _n H _m + nO ^2- → nCO + (m / 2) H ₂ + 2ne ⁻ ) with oxygen (oxide ion). Anode 112 is, for example, a LaCrO ₃ type oxide having a perovskite structure, with the addition of Sr to La site, is formed of a composite oxide or the like is added to the Cr site Ni.

The oxygen sensor 240 (FIG. 1) is a sensor attached to the reforming gas discharge pipe 230 and measures the oxygen partial pressure Px of the reforming gas RG discharged from the fuel chamber S2 of the oxygen permeable membrane structure 110. .. In this embodiment, a zirconia type oxygen sensor is used as the oxygen sensor 240. The zirconia type oxygen sensor is a sensor that measures the oxygen partial pressure of a gas based on the electromotive force generated in zirconia, which is an oxide ion conductor, and can measure the oxygen partial pressure with high accuracy. The relationship between the output voltage of the oxygen sensor 240 (zirconia type oxygen sensor) and the oxygen partial pressure Px of the reforming gas RG is expressed by the following equation (1).
E =-(RTs / 4F) ln {Px / Po} ... (1)
(However, Px: oxygen partial pressure of reformed gas RG, Po: oxygen partial pressure of gas into which air is introduced (= 0.21 atm), R: gas constant, F: Faraday constant, Ts: sensor measurement temperature (absolute) Temperature), E: Electromotive force)

The oxygen partial pressure Px of the reformed gas RG can change to the temperature. Px in the above formula (1) is the reaction formula H ₂ O + CO ₂ ⇔ H ₂ + CO + O ₂
When the equilibrium constant at the sensor measurement temperature Ts is Ks, it is expressed by the following equation (2).
Px = {([H ₂ O] x [CO ₂ ]) / ([H ₂ ] x [CO])} x Ks ... (2)
The oxygen partial pressure Px (1000) at a reference temperature of 1000 ° C. is represented by the following formula (3) using the equilibrium constant K (1000) at a reference temperature of 1000 ° C. in the above reaction formula.
Px (1000) = Px · K (1000) / Ks ... (3)
Here, the equilibrium constant K (T) at an arbitrary temperature T is expressed by the following equation (4) using the enthalpy change ΔH (T) and the entropy change ΔS (T).
K (T) = exp (-(ΔH (T) -T · ΔS (T)) / (RT)) ... (4)
In addition, ΔH (T) and ΔS (T) may be calculated from the constant pressure molar heat capacity Cp (T) described in the Electrochemical Handbook (Maruzen Publishing Co., Ltd., 6th edition) and the like.

The control unit 250 (FIG. 1) is composed of, for example, a computer including a CPU and a storage unit, and controls the reformer 10. For example, the control unit 250 acquires an oxygen partial pressure signal Sp indicating the oxygen partial pressure Px of the reforming gas RG from the oxygen sensor 240, sets the supply amount of the fuel gas FG based on the oxygen partial pressure signal Sp, and sets the fuel gas. The fuel supply amount control for transmitting the supply amount command signal Sf instructing the supply amount of the fuel gas FG to the supply unit 210 is executed. Fuel supply control will be described in detail later.

A-2. Operation of reformer 10:
In the reformer 10, when air is supplied to the air chamber S1, the reaction of ionizing oxygen in the air by the catalytic effect of the air electrode 113 facing the air chamber S1 (1 / 2O ₂ + 2e ⁻ → O ^2- ) Occurs. The oxide ions generated by this reaction move to the fuel chamber S2 side in the oxygen permeable membrane 111 having oxide ion conductivity (see FIG. 3).

Further, when the fuel gas FG is supplied from the fuel gas supply unit 210 to the reaction unit 100 via the fuel gas supply pipe 220, the supplied fuel gas FG is an oxygen permeable film structure via the supply side connection pipe 121. Enter the fuel chamber S2 inside the 110. When the fuel gas FG that has entered the fuel chamber S2 passes through the inside of the support 114 that is a porous member and reaches the fuel electrode 112, the hydrocarbon and oxygen permeable film 111 in the fuel gas FG due to the catalytic effect of the fuel electrode 112. partial oxidation reforming reaction with oxygen that is transmitted through the (oxide ^{_{ions) (C n H m + nO}} 2- → nCO + (m / 2) H 2 + 2ne -) occurs. By this reaction, the fuel gas FG containing hydrocarbon is reformed into the reformed gas RG containing hydrogen and carbon monoxide. The electrons generated by the partial oxidation reforming reaction move to the air chamber S1 side in the oxygen permeable membrane 111 having electrical conductivity, and are subjected to the above-mentioned oxygen ionization reaction (see FIG. 3).

The reformed gas RG generated in the reaction unit 100 is taken out from the reformed gas discharge pipe 230 via the discharge side connecting pipe 122. The extracted reformed gas RG (gas containing hydrogen and carbon monoxide) is used, for example, for power generation in a fuel cell, or further converts hydrogen and carbon monoxide into hydrocarbons to produce a liquid hydrocarbon fuel. It is used for GTL.

A-3. Fuel flow control of reformer 10:
In the fuel chamber S2 of the reformer 10, in addition to the partial oxidation reforming reaction of the above-mentioned hydrocarbon, complete oxidation reaction _{(C n H m + (n} + m / 4) O 2 → (m / 2) H 2 O + nCO 2 ) Can also occur (for convenience, represented by the reaction of hydrocarbons with oxygen). Therefore, the reforming gas RG produced by the reformer 10 may contain water and carbon dioxide in addition to hydrogen and carbon monoxide. The higher the concentration of water and carbon dioxide in the reformed gas RG, the lower the concentration of hydrogen and carbon monoxide that can be used in the fuel cell and GTL, which is not preferable. In the following description, the ratio of the volume ratio of hydrogen to the total of the volume ratio of hydrogen and the volume ratio of water in the reformed gas RG is referred to as hydrogen selectivity SP1 (%). The ratio of the volume ratio of carbon monoxide to the total of the volume ratio of carbon monoxide and the volume ratio of carbon dioxide in the reformed gas RG is called carbon monoxide selectivity SP2 (%). It is preferable that both hydrogen-selective SP1 and carbon monoxide-selective SP2 are high.

In order to increase the hydrogen selectivity SP1 and the carbon monoxide selectivity SP2, the inventor of the present application permeates the amount of hydrocarbons supplied to the fuel chamber S2 of the reformer 10 from the air chamber S1 through the oxygen permeation film 111. It was found that it is important to make the amount slightly larger than the stoichiometric amount of the partial oxidation reforming reaction obtained from the amount of oxygen supplied to the fuel chamber S2. This is because, due to thermodynamic equilibrium, when the abundance of hydrocarbons in the fuel chamber S2 is larger than the stoichiometric amount, the surplus hydrocarbons react with water and carbon dioxide to generate hydrogen and carbon monoxide. Is considered to be. However, if the amount of hydrocarbons is excessive, among the hydrocarbons supplied to the fuel chamber S2, the amount of hydrocarbons discharged from the fuel chamber S2 without being subjected to the reaction becomes large, and the reforming apparatus 10 It is not preferable because it reduces efficiency. In the following description, the ratio of hydrocarbon consumption (difference between the amount of hydrocarbon input and the amount of hydrocarbon contained in the reforming gas RG) to the amount of hydrocarbon input (the amount of hydrocarbon contained in the fuel gas FG). Is called a hydrocarbon conversion rate IR (%). The higher the hydrocarbon conversion rate IR, the higher the efficiency of the reformer 10, which is preferable.

The inventor of the present application has achieved both improvement of hydrogen selectivity SP1 and carbon monoxide selectivity SP2 and improvement of hydrocarbon conversion rate IR by executing the fuel flow rate control of the reformer 10 described below. We have found that it can be realized easily and stably. Hereinafter, the fuel flow rate control of the reformer 10 will be described.

FIG. 4 is a flowchart showing the flow of fuel flow rate control of the reformer 10. First, the control unit 250 of the reformer 10 causes the fuel gas supply unit 210 to start supplying the fuel gas FG (S110). Next, the control unit 250 acquires the oxygen partial pressure signal Sp from the oxygen sensor 240, and identifies the oxygen partial pressure Px of the reforming gas RG based on the oxygen partial pressure signal Sp (S120).

Next, the control unit 250 determines whether or not the oxygen partial pressure Px of the specified reformed gas RG is within the preset appropriate range, and the oxygen partial pressure Px of the reformed gas RG is out of the appropriate range. When it is determined that the fuel gas FG is supplied, a process of changing the supply amount of the fuel gas FG is performed (S130 to S160). Here, the above-mentioned appropriate range of the oxygen partial pressure Px of the reformed gas RG is set so that the improvement of the hydrogen selectivity SP1 and the carbon monoxide selectivity SP2 and the improvement of the hydrocarbon conversion rate IR can be compatible with each other. Has been done.

More specifically, the upper limit value Pmax of the above-mentioned appropriate range is set in advance with the first condition that the hydrogen selectivity SP1 becomes equal to or higher than the preset first reference value Th1 and the carbon monoxide selectivity SP2. It is set so that both the second condition that the second reference value is Th2 or more and the second condition are satisfied. The state in which the oxygen partial pressure Px of the reformed gas RG is too high is a state in which the reaction amount of the partial oxidation reforming reaction in the fuel chamber S2 is small because the amount of hydrocarbons supplied to the fuel chamber S2 is small. Further, in this state, most of the water and carbon dioxide generated in the fuel chamber S2 are discharged from the fuel chamber S2 as they are without reacting with the hydrocarbon, and the hydrogen selectivity SP1 and the carbon monoxide selectivity SP2 are low. .. Therefore, by setting the upper limit value Pmax in the appropriate range, it is possible to maintain a high state of hydrogen selectivity SP1 and carbon monoxide selectivity SP2. The first reference value Th1 is preferably set to 95 (%). The second reference value Th2 is preferably set to 96 (%). Further, the upper limit value Pmax in the appropriate range is preferably set to 1 × 10 ^-17 (atm), more preferably 1 × 10 ^-19 (atm), in terms of the reference temperature of 1000 ° C.

Further, the lower limit value Pmin of the appropriate range is set so as to satisfy the third condition that the hydrocarbon conversion rate IR is equal to or higher than the preset third reference value Th3. The state in which the oxygen partial pressure Px of the reformed gas RG is too low is a state in which the reaction amount of the partial oxidation reforming reaction in the fuel chamber S2 is large because the amount of hydrocarbons supplied to the fuel chamber S2 is large. Further, in this state, most of the hydrocarbons supplied to the fuel chamber S2 are discharged from the fuel chamber S2 as they are, and the hydrocarbon conversion rate IR is low. Therefore, by setting the lower limit value Pmin in the appropriate range, it is possible to maintain a state in which the hydrocarbon conversion rate IR is high. The third reference value Th3 is preferably set to 60 (%), more preferably 75 (%). Further, the lower limit value Pmin in the appropriate range is preferably set to 1 × ^10-23 (atm), more preferably 1 × ^10-22 (atm), in terms of the reference temperature of 1000 ° C.

The specific contents of the process of changing the supply amount of the fuel gas FG according to the oxygen partial pressure Px of the reformed gas RG are as follows. The control unit 250 determines whether or not the oxygen partial pressure Px of the reforming gas RG is lower than the lower limit value Pmin of the appropriate range (S130), and the oxygen partial pressure Px of the reforming gas RG is the lower limit value Pmin of the appropriate range. If it is determined to be lower (S130: YES), the fuel gas supply unit 210 is instructed to reduce the supply amount of the fuel gas FG (S140). As a result, the amount of hydrocarbons supplied to the fuel chamber S2 is reduced, and as a result, the reaction amount of the partial oxidation reforming reaction in the fuel chamber S2 is reduced, and the oxygen partial pressure Px of the reformed gas RG is increased. , The amount of hydrocarbons discharged from the fuel chamber S2 is reduced, and the hydrocarbon conversion rate IR is increased. After that, the control unit 250 waits for the elapse of the predetermined time (S170), and when the predetermined time elapses (S170: YES), the control unit 250 re-executes the process of S120 described above.

Further, when the control unit 250 determines that the oxygen partial pressure Px of the reforming gas RG is equal to or higher than the lower limit value Pmin of the appropriate range (S130: NO), the oxygen partial pressure Px of the reforming gas RG is described above. If it is determined whether or not it is higher than the upper limit value Pmax of the appropriate range (S150) and the oxygen partial pressure Px of the reforming gas RG is higher than the upper limit value Pmax of the appropriate range (S150: YES), the fuel gas The supply unit 210 is instructed to increase the supply amount of the fuel gas FG (S160). As a result, the amount of hydrocarbons supplied to the fuel chamber S2 increases, and as a result, the reaction amount of the partial oxidation reforming reaction in the fuel chamber S2 increases, and the oxygen partial pressure Px of the reformed gas RG decreases. , Excess hydrocarbons react with water and carbon dioxide to produce hydrogen and carbon monoxide, increasing hydrogen selectivity SP1 and carbon monoxide selectivity SP2. After that, the control unit 250 waits for the elapse of the predetermined time (S170), and when the predetermined time elapses (S170: YES), the control unit 250 re-executes the process of S120 described above.

When the control unit 250 determines that the oxygen partial pressure Px of the reformed gas RG is within the above-mentioned appropriate range (S130: NO and S150: NO), the control unit 250 changes the supply amount of the fuel gas FG described above. (S140, S160) is not executed. In this case, the control unit 250 determines whether or not the operation end instruction of the reformer 10 has been received (S180), and if it determines that the operation end instruction has not been received (S180: NO), it is predetermined. Waiting for the passage of time (S170: YES), the above-described processing of S120 is executed again. When the control unit 250 determines that the operation end instruction has been received (S180: YES), the control unit 250 ends the fuel flow rate control process.

A-4. Effect of this embodiment:
As described above, the reformer 10 of the present embodiment includes an oxygen permeable membrane 111, a fuel gas supply unit 210, and a control unit 250. The oxygen permeable film 111 has oxide ion conductivity and electron conductivity or hole conductivity, is arranged between the air chamber S1 and the fuel chamber S2, and has the air chamber S1 and the fuel chamber S2. Oxygen is permeated from the air chamber S1 to the fuel chamber S2 using the difference in oxygen partial pressure between them as a driving force. Further, the fuel gas supply unit 210 supplies the fuel gas FG to the fuel chamber S2. Further, the control unit 250 sets the fuel so that the oxygen partial pressure Px of the reformed gas RG discharged from the fuel chamber S2 is within an appropriate range of the preset lower limit value Pmin or more and the upper limit value Pmax or less. The reaction amount of the partial oxidation reforming reaction in the chamber S2 is controlled. Therefore, according to the reforming apparatus 10 of the present embodiment, the reforming gas RG is reformed as the oxygen partial pressure Px of the reforming gas RG becomes excessively low by simple control based on the oxygen partial pressure Px of the reforming gas RG. The reformed gas as the oxygen partial pressure Px of the reformed gas RG becomes excessively high while suppressing the increase in the amount of hydrocarbons contained in the gas RG and the decrease in the efficiency of the reformer 10. It is possible to prevent the composition of RG from becoming unfavorable. Therefore, according to the reformer 10 of the present embodiment, the composition of the reformed gas RG is stably hydrogenated while suppressing the decrease in efficiency by suppressing the amount of hydrocarbons contained in the reformed gas RG. It can have a good composition with a high content ratio of carbon monoxide.

More specifically, in the reformer 10 of the present embodiment, the control unit 250 controls the amount of fuel gas FG supplied to the fuel chamber S2 by the fuel gas supply unit 210, thereby partially oxidizing the fuel chamber S2. The reaction amount of the reforming reaction is controlled. Therefore, according to the reforming apparatus 10 of the present embodiment, the reaction amount of the partial oxidation reforming reaction in the fuel chamber S2 can be controlled by simple control, and the reforming gas can be suppressed while suppressing a decrease in efficiency. The composition can be stably adjusted to a good composition.

Further, in the reforming apparatus 10 of the present embodiment, the upper limit value Pmax of the appropriate range of the oxygen partial pressure Px of the reformed gas RG is the first reference value Th1 or more in which the hydrogen selectivity SP1 is set in advance. It is a value set so as to satisfy both the condition 1 and the second condition that the carbon monoxide selectivity SP2 becomes the preset second reference value Th2 or more. Therefore, according to the reforming apparatus 10 of the present embodiment, the composition of the reformed gas RG can be stably set to a good composition having high hydrogen selectivity SP1 and carbon monoxide selectivity SP2.

The first reference value Th1 is preferably 95 (%). In this way, the composition of the reformed gas RG can be a very good composition with a hydrogen selectivity SP1 of 95 (%) or more. Further, the second reference value Th2 is preferably 96 (%). By doing so, the composition of the reformed gas RG can be stably made into a good composition in which the carbon monoxide selectivity SP2 is 96 (%) or more, which is very high.

Further, in the reforming apparatus 10 of the present embodiment, the lower limit value Pmin of the appropriate range of the oxygen partial pressure Px of the reforming gas RG is said to be equal to or higher than the third reference value Th3 in which the hydrocarbon conversion rate IR is set in advance. It is a value set so that the third condition is satisfied. Therefore, according to the reforming apparatus 10 of the present embodiment, the hydrocarbon conversion rate IR can be stably increased to improve the efficiency.

The third reference value Th3 is preferably 75 (%). By doing so, it is possible to stably realize the reforming apparatus 10 having a hydrocarbon conversion rate IR of 75 (%) or more and very high efficiency.

Further, since the reforming apparatus 10 of the present embodiment includes an oxygen sensor 240 for measuring the oxygen partial pressure Px of the reforming gas RG discharged from the fuel chamber S2, the oxygen partial pressure of the reforming gas RG is measured by a simple means. Px can be measured. Further, in the reforming apparatus 10 of the present embodiment, the oxygen sensor 240 is a zirconia-type oxygen sensor that measures the oxygen partial pressure Px of the reformed gas RG based on the electromotive force generated in the oxide ion conductor zirconia. Therefore, the oxygen partial pressure Px of the reformed gas RG can be measured accurately by a simple means.

In the above embodiment, the control unit 250 is a portion in the fuel chamber S2 so that the total volume ratio of hydrogen, carbon monoxide, and hydrocarbon in the reformed gas RG is 95 (%) or more. It is preferable to control the reaction amount of the oxidation reforming reaction. By doing so, the composition of the reformed gas RG can be stably made into a good composition having a low content ratio of water and carbon dioxide.

In the above embodiment, the control unit 250, and the ratio of the volume ratio of hydrogen to the volume ratio of carbon monoxide to total reformed gas RG (hereinafter, referred to as _"H 2 / CO ratio Rhc") is 1.9 or more It is preferable to control the reaction amount of the partial oxidation reforming reaction in the fuel chamber S2 so as to be 2.1 or less. In this way, the composition of the reformed gas RG can be stably set to substantially the same composition as the hydrogen-carbon monoxide ratio of the raw material gas required for saturated hydrocarbons synthesized in the Fischer-Tropsch reaction process, for example. Can be done.

A-5. Performance evaluation:
In order to evaluate the performance of the reformer equipped with the oxygen permeable membrane, the reformer 300 for evaluation is created, and the performance is examined by examining the characteristics of the reformer gas RG when the reformer 300 is operated under various conditions. Evaluation was performed. First, the reformer 300 for evaluation will be described.

(Preparation of oxygen permeable membrane structure)
Lanthanum oxide (La ₂ O ₃ ), strontium carbonate (SrCO ₃ ), and chromium oxide (Cr ₂ O ₃ ) powders are prepared as raw material powders for the oxygen permeable film, and these raw material powders are used as the ratio of metal elements. Was weighed at a ratio of La _0.8 Sr _0.2 CrO _3-z . In addition, z in the composition formula is an oxygen non-stoichiometric ratio representing the amount of oxygen deficiency (the same applies hereinafter). Ethanol was added to these raw material powders, and wet mixing and pulverization was carried out for 15 hours using a ceramic ball and a resin pot. Then, it was dried in hot water to remove ethanol, and the obtained mixed powder was calcined at 1500 ° C. for 24 hours to obtain a powder of La _0.8 Sr _0.2 CrO _3-z which is a calcined powder.

Furthermore, commercial _{ScSZ (Sc 0.1 Ce 0.01 Zr 0.89} O 2) powder and _La 0.8 _Sr 0.2 _{CrO 3-z} and _La 0.8 _Sr 0.2 CrO ₃ in a mixture of _The powder containing the above-mentioned calcined powder is mixed with ScSZ so that the mixing ratio of _−z is 30 (vol%) to obtain a mixed powder of ScSZ and La _0.8 Sr _0.2 CrO _3-z. It was. Further, hand press molding was performed so as to form a disc having a diameter of 20 mm, pressure was applied at 1000 kg / cm ² with a hydrostatic press, and firing was performed at 1500 ° C. for 24 hours to obtain a sintered body. Then, both sides were ground and polished with a surface grinder to a thickness of 200 μm.

Further, as the fuel electrode material, a commercially available nickel oxide powder and a commercially available ScSZ (Sc _0.1 Ce _0.01 Zr _0.89 O ₂ ) powder are mixed so as to have a volume ratio of 50:50. , Binder, amine-based dispersant, and plasticizer were added to make a paste using butyl carbitol as a solvent. The above-mentioned disc-shaped sintered body was coated with a paste of a fuel electrode material by screen printing, and then baked at 1400 ° C. for 1 hour. As a result, a laminate of an oxygen permeable membrane and a fuel electrode was obtained.

Further, as an air electrode material, a commercially available La _0.8 Sr _0.2 MnO ₃ and a commercially available ScSZ (Sc _0.1 Ce _0.01 Zr _0.89 O ₂ ) powder are used in a volume ratio of 70:30. As described above, a binder, an amine-based dispersant, and a plasticizer were added to form a paste using butyl carbitol as a solvent. The paste of the air electrode material was applied to the surface of the oxygen permeable film in the above-mentioned laminate of the oxygen permeable film and the fuel electrode by screen printing, and then baked at 1300 ° C. for 1 hour. As a result, an oxygen permeable membrane structure 310, which is a laminate of an oxygen permeable membrane, a fuel electrode, and an air electrode, was obtained.

(Reformer 300 for evaluation)
FIG. 5 is an explanatory diagram schematically showing the configuration of the reformer 300 for evaluation. The reformer 300 includes an oxygen permeable film structure 310, two transparent quartz tubes (first transparent quartz tube 331 and a second transparent quartz tube 332), and two alumina tubes (first alumina tube 321 and a first alumina tube). It includes a 2 alumina tube 322), an electric furnace 350, and a thermoelectric pair 340.

The first transparent quartz tube 331 and the second transparent quartz tube 332 are arranged so as to be coaxial with each other. An oxygen permeable membrane structure 310 is arranged and joined between the first transparent quartz tube 331 and the second transparent quartz tube 332 so that the fuel electrode side faces the first transparent quartz tube 331 side (upper side). Has been done. When joining the first transparent quartz tube 331 and the second transparent quartz tube 332 to the oxygen permeable film structure 310, a gold thin film ring 302 having an inner diameter of 10 mm is placed on the oxygen permeable film structure 310 to form a thin film. With the first transparent quartz tube 331 and the second transparent quartz tube 332 pressed against the ring 302, the temperature was raised to 1050 ° C. to soften the gold and secure the gas sealability.

The first alumina tube 321 is arranged in the inner space of the first transparent quartz tube 331. One end of the first alumina tube 321 faces the fuel electrode surface of the oxygen permeable membrane structure 310, and methane is supplied to the vicinity of the fuel electrode of the oxygen permeable membrane structure 310. Further, the second alumina tube 322 is arranged in the inner space of the second transparent quartz tube 332. One end of the second alumina tube 322 faces the air electrode surface of the oxygen permeable membrane structure 310, and supplies air to the vicinity of the air electrode of the oxygen permeable membrane structure 310.

The electric furnace 350 is arranged so as to surround the oxygen permeable membrane structure 310 arranged between the first transparent quartz tube 331 and the second transparent quartz tube 332, and uniformly heats the oxygen permeable membrane structure 310. The thermocouple 340 is arranged in the second alumina tube 322 at a position close to the oxygen permeable membrane structure 310, and measures the temperature of the oxygen permeable membrane structure 310.

(Evaluation methods)
FIG. 6 is an explanatory diagram showing the performance evaluation result. In this performance evaluation, in the reformer 300, methane as a fuel gas FG is supplied to the fuel electrode side of the oxygen permeable film structure 310 via the first alumina tube 321 and oxygen is supplied through the second alumina tube 322. By supplying air to the air electrode side of the permeable film structure 310, a reforming reaction was carried out on the fuel electrode surface of the oxygen permeable film structure 310 to generate a modified gas RG. At this time, the electric furnace 350 was controlled to maintain the temperature (operating temperature) of the oxygen permeable membrane structure 310 measured by the thermocouple 340 at 1000 ° C. The composition of the reformed gas RG taken out from the first transparent quartz tube 331 was measured using a quadrupole mass analyzer (not shown) while changing the supply amount of methane. The composition of the measured reformed gas RG, the above-mentioned _H 2 / CO ratio Rhc, hydrogen-selective SP1, carbon monoxide selectivity SP2, was calculated hydrocarbon conversion IR. Further, the oxygen partial pressure Px of the reformed gas RG was measured using a zirconia type oxygen sensor (not shown).

(Evaluation results)
As shown in FIG. 6, the methane supply amount (ml / min) is different from each other in each of the conditions 1 to 18. Specifically, the methane supply amount is gradually increased from condition 1 to condition 18. In all of the conditions 1 to 18, the operating temperature (the temperature of the oxygen permeable membrane structure 310) is 1000 ° C.

As shown in FIG. 6, the smaller the methane supply amount, the higher the oxygen partial pressure Px of the reformed gas RG, the lower the hydrogen selective SP1 and the carbon monoxide selective SP2, and the higher the hydrocarbon conversion rate IR. , H ₂ / CO ratio Rhc tends to be small. On the contrary, as the amount of methane supplied increases, the oxygen partial pressure Px of the reformed gas RG decreases, the hydrogen selectivity SP1 and carbon monoxide selectivity SP2 increase, the hydrocarbon conversion rate IR decreases, and H ₂ / The CO ratio Rhc tends to increase.

Under conditions 5 to 15, the oxygen partial pressure Px of the reformed gas RG is in the range of 1 × 10 ^-23 (atm) or more and 1 × 10 ^-17 (atm) or less. Under conditions 5 to 15, the hydrogen selectivity SP1 is as good as 95 (%) or more, and the carbon monoxide selectivity SP2 is also as good as 96 (%) or more. _Moreover, H 2 / CO ratio Rhc is also good to be in the range of 2.0 ± 0.05, a reasonable good as hydrocarbon conversion IR also 60% or higher. Further, under these conditions, the total volume ratio of hydrogen, carbon monoxide, and methane in the reformed gas RG is 95 (%) or more, and it can be used as a completely oxidized fuel or a synthetic gas. There are fewer impurities such as low-value water and carbon dioxide. From the above, as appropriate range of oxygen partial pressure Px of the reformed gas RG during control of the above-described reformer, at ^{1000 ℃, 1 × 10 -23 (} atm) or more, 1 × ¹⁰ -17 (atm ) It can be said that it is preferable that the following range is set.

Further, among the conditions 5 to 15, particularly under the conditions 5 to 13, the hydrocarbon conversion rate IR is as good as 75 (%) or more, the surplus amount of methane is relatively small, and hydrogen and carbon monoxide can be effectively produced. It can be said that it has been generated. Therefore, the appropriate range of the oxygen partial pressure Px of the reforming gas RG when controlling the reforming apparatus described above is 9 × ^10-23 (atm) or more and 1 × 10 ^-17 (atm) or less at 1000 ° C. It can be said that it is more preferable that the range is set.

Also, of the conditions 5-13, in particular conditions 8-12, hydrogen-selective SP1 and carbon monoxide selectivity SP2 are both 99.5 (%) or more and very _good, also H 2 / CO ratio Rhc 2 It is ideal at 0.0, and the hydrocarbon conversion rate IR is extremely good at 85 (%) or more. As described above, it can be said that the ideal modification was performed under the conditions 8 to 12. Therefore, the appropriate range of the oxygen partial pressure Px of the reforming gas RG when controlling the reforming apparatus described above is 1 × ^10-22 (atm) or more and 1 × ^10-19 (atm) or less at 1000 ° C. It can be said that it is more preferable that the range is set.

It can be said that the conditions 1 to 4 are not preferable because the hydrogen selective SP1 and the carbon monoxide selective SP2 are low because the methane supply amount is extremely small. In particular, for the condition 1, _2, H 2 / CO ratio Rhc is not preferable less than 1.9, since very low even hydrogen-selective SP1 and carbon monoxide selectivity SP2, it can be said that no particular preferred. Further, it can be said that the conditions 16 to 18 are not preferable because the hydrocarbon conversion rate IR is low because the methane supply amount is extremely large.

In this performance evaluation, methane was used as the hydrocarbon, but even when other hydrocarbons (including a mixed gas of methane and other hydrocarbons) are used, the above-mentioned reformer is controlled. It can be said that it is preferable to adopt an appropriate range of the oxygen partial pressure Px of the reformed gas RG. In the reformer provided with the oxygen permeable membrane, the partial oxidation reaction represented by the following formula (11) and the complete oxidation reaction represented by the following formula (12) occur. Each coefficient (α, β, γ, δ, ε, ζ) varies depending on the type of hydrocarbon used, but if the hydrocarbon is ideally used in the reactions (11) and (12), it will be hydrocarbonized. It is considered that the reaction of the following formula (13) occurs regardless of the type of hydrogen. One of the features of the present invention is that control is performed so that the hydrocarbons react ideally in order to achieve both improvement of hydrogen selectivity SP1 and carbon monoxide selectivity SP2 and improvement of hydrocarbon conversion rate IR. It can be said that the above compatibility can be achieved by adopting the appropriate range of the oxygen partial pressure Px of the reformed gas RG described above regardless of the type of hydrocarbon. If the amount of hydrocarbons contained in the reforming gas RG discharged from the reformer is equal to or less than a predetermined value, it can be regarded as the following formula (13). Therefore, the oxygen content of the reforming gas RG described above It can be said that it is preferable to adopt an appropriate range of pressure Px.
CnHm + αO ₂ → βH ₂ + γCO ... (11)
CnHm + δO ₂ → εH ₂ O + ζCO ₂ ... (12)
H ₂ O + CO ₂ → H ₂ + CO + O ₂ ... (13)

Further, when the volume ratio of methane to the total hydrocarbon in the fuel gas FG is 50 (%) or more, the appropriate range of the oxygen partial pressure Px of the reformed gas RG when controlling the reformer described above is adopted. It can be said that it is particularly preferable to do so.

A-6. Example:
Examples of the reformer 10 described above will be described.

(Method of manufacturing oxygen permeable membrane structure 110)
To the calcium-stabilized zirconia (CSZ) powder, add a cellulosic binder and polymethylmethacrylate (PMMA) bead powder as a pore-forming material, mix well, and add water to make clay. Mixed up to. The amount of the pore-forming material added was set so that 60 (vol%) was pores with respect to the volume of the CSZ powder. The clay-like mixture was put into an extrusion molding machine to prepare a cylindrical support molded body having an outer diameter of 12 mm.

Next, La _0.8 Sr _0.2 Cr _0.85 Ni _0.15 O _3-z was prepared as a fuel electrode constituent material. As raw materials, powders of lanthanum oxide (La ₂ O ₃ ), strontium carbonate (SrCO ₃ ), chromium oxide (Cr ₂ O ₃ ), and nickel oxide (NiO) were used. These raw material powders were weighed so that the ratio of metal elements was the ratio of the above composition formula. Ethanol was added to these raw material powders, and wet mixing and pulverization was carried out using a ceramic ball and a resin pot for 15 hours. Then, it was dried in hot water to remove ethanol, and the obtained mixed powder was calcined at 1500 ° C. for 24 hours to obtain La _0.8 Sr _0.2 Cr _0.85 Ni _0.15 O which is a calcined powder. _{A 3-z} powder was obtained. The obtained La _0.8 Sr _0.2 Cr _0.85 Ni _0.15 O _3-z powder and a commercially available ScSZ (Sc _0.1 Ce _0.01 Zr _0.89 O ₂ ) powder were used. , The volume ratio was 50:50, and polyvinyl butyral, an amine-based dispersant, and a plasticizer were mixed with methyl ethyl ketone and ethanol as solvents to prepare a coating slurry for forming a fuel electrode.

Further, in order to form an oxygen permeable membrane, a mixed powder of ScSZ and La _0.8 Sr0.2CrO _3-z produced by the same method as the production method in the performance evaluation described above, polyvinyl butyral, and an amine-based dispersion. The agent and the plasticizer were mixed with methyl ethyl ketone and ethanol as solvents to prepare a coating slurry for forming an oxygen permeable membrane.

Next, the above-mentioned molded body for a support is cut to a predetermined length, masked at a position where a fuel electrode is not formed, immersed in the above-mentioned slurry for coating for forming a fuel electrode, and then slowly. By pulling up, a fuel electrode precursor was formed on the surface of the support molded body. Further, after masking the position where the oxygen permeable film is not formed, the fuel electrode is immersed in the oxygen permeable film forming coating slurry and then slowly pulled up to form the fuel electrode formed on the surface of the support molded body. An oxygen permeable membrane precursor was formed on the surface of the precursor. Then, at 1500 ° C., the molded body for the support, the fuel electrode precursor, and the oxygen permeable film precursor are simultaneously fired to provide a tubular sintered body having the fuel electrode 112, the oxygen permeable film 111, and the support 114. I got a body.

Further, in order to form an air electrode, a commercially available La _0.8 Sr _0.2 MnO ₃ powder and a commercially available ScSZ (Sc _0.1 Ce _0.01 Zr _0.89 O ₂ ) powder are mixed in a volume ratio of 70: The powder mixed so as to be 30, polyvinyl butyral, an amine-based dispersant, and a plasticizer were mixed with methyl ethyl ketone and ethanol as solvents to prepare a slurry for forming an air electrode. The above-mentioned tubular sintered body was masked at a position where an air electrode was not formed, immersed in a slurry for forming an air electrode, and then slowly pulled up to form an air electrode precursor. Then, the air electrode 113 was produced by performing a baking treatment at 1300 ° C. By the above method, an oxygen permeable membrane structure 110 including a support 114, a fuel electrode 112, an oxygen permeable membrane 111, and an air electrode 113 was produced.

The reformer 10 described above is configured by using the produced oxygen permeable film structure 110, and the oxygen partial pressure Px of the reformed gas RG measured by the oxygen sensor 240 provided in the reformed gas discharge pipe 230 is 1. The reforming operation was performed while controlling the supply amount of methane as the fuel gas FG so as to be 0 × ^10-21 (atm). As a result, the reformed gas RG had a composition of 2% methane, 65% hydrogen, and 32% carbon monoxide, and the operation could be performed in a substantially stable state. From the above, it was confirmed that stable reforming can be performed by controlling the supply amount of methane based on the oxygen partial pressure Px of the reformed gas RG.

B. Modification example:
The technique disclosed in the present specification is not limited to the above-described embodiment, and can be transformed into various forms without departing from the gist thereof. For example, the following modifications are also possible.

The configuration of the reformer 10 in the above embodiment is merely an example and can be variously modified. For example, in the above embodiment, the oxygen permeable membrane structure 110 is composed of a support 114, a fuel electrode 112, an oxygen permeable membrane 111, and an air electrode 113, but the oxygen permeable membrane structure 110 is The support 114 may not be provided, or at least one of the fuel pole 112 and the air pole 113 may not be provided.

Further, in the above embodiment, the oxygen permeable membrane 111 is a member having a substantially cylindrical shape, but the shape of the oxygen permeable membrane 111 can be variously deformed, and may be, for example, a flat plate shape.

Further, in the above embodiment, the inner peripheral side of the oxygen permeable membrane 111 (oxygen permeable membrane structure 110) is used as the fuel chamber S2 and the outer peripheral side is used as the air chamber S1, but on the contrary, the oxygen permeable membrane 111 is used. The inner peripheral side may be used as the air chamber S1 and the outer peripheral side may be used as the fuel chamber S2. Further, in the reformer 10, it is also possible to adopt a configuration in which a plurality of oxygen permeable membranes 111 are laminated and air chambers S1 and fuel chambers S2 are alternately provided between the laminated oxygen permeable membranes 111.

Further, the material constituting each member in the above embodiment is merely an example, and each member may be composed of another material.

Further, in the above embodiment, the zirconia type oxygen sensor is used as the oxygen sensor 240 for measuring the oxygen partial pressure Px of the reformed gas RG discharged from the fuel chamber S2 of the oxygen permeable film structure 110. (For example, a galvanized battery type oxygen sensor or a magnetic type oxygen sensor) may be used. Further, in the above embodiment, instead of the oxygen sensor 240, the oxygen partial pressure Px of the reformed gas RG may be measured by another means (for example, a gas analyzer).

Further, in the above embodiment, air is supplied to the air chamber S1, but if it is a gas containing oxygen, a gas other than air may be supplied.

Further, the content of the fuel flow rate control of the reformer 10 in the above embodiment is merely an example and can be variously modified. For example, in the above embodiment, the upper limit value Pmax of the appropriate range of the oxygen partial pressure Px of the reformed gas RG is the first condition that the hydrogen selectivity SP1 is equal to or higher than the preset first reference value Th1. It is said that both the second condition that the carbon monoxide selectivity SP2 becomes equal to or higher than the preset second reference value Th2 and the second condition are satisfied, but the first condition and the second condition are satisfied. It may be set so that at least one of the above is satisfied.

Further, the values of the upper limit value Pmax and the lower limit value Pmin of the appropriate range of the oxygen partial pressure Px of the reformed gas RG in the above embodiment, and the first reference values Th1 and the second reference value to be referred to for setting the upper limit value Pmax. The value of the reference value Th2 and the value of the third reference value Th3 referred to for setting the lower limit value Pmin are merely examples, and may be appropriately set according to various conditions.

Further, in the above embodiment, the control unit 250 controls the reaction amount of the partial oxidation reforming reaction in the fuel chamber S2 by controlling the supply amount of the fuel gas FG to the fuel chamber S2 by the fuel gas supply unit 210. However, instead of or in combination with this, the reaction amount of the partial oxidation reforming reaction in the fuel chamber S2 may be controlled by another method. For example, the control unit 250 may control the reaction amount of the partial oxidation reforming reaction in the fuel chamber S2 by controlling the temperature of the reaction unit 100 (fuel chamber S2). By raising the temperature of the reaction unit 100 with a heater (not shown), the reaction amount of the partial oxidation reforming reaction in the fuel chamber S2 can be increased.

10: Reformer 100: Reaction unit 110: Oxygen permeable film structure 111: Oxygen permeable film 112: Fuel electrode 113: Air electrode 114: Support 121: Supply side connection pipe 122: Discharge side connection pipe 130: Containment pipe 210 : Fuel gas supply unit 211: Gas source 212: Flow control unit 220: Fuel gas supply pipe 230: Reform gas discharge pipe 240: Oxygen sensor 250: Control unit 300: Reformer 302: Thin film ring 310: Oxygen permeable film structure Body 321: 1st alumina tube 322: 2nd alumina tube 331: 1st transparent quartz tube 332: 2nd transparent quartz tube 340: Thermoelectric pair 350: Electric furnace

Claims (13)

In a reformer that uses a partial oxidation reforming reaction between hydrocarbons and oxygen to generate a reforming gas containing carbon monoxide and hydrogen from a fuel gas containing hydrocarbons.
It has oxide ion conductivity and electron conductivity or hole conductivity, and is arranged between the first space and the second space, and the first space and the second space. An oxygen permeable film that allows oxygen to permeate from the first space to the second space using the difference in oxygen partial pressure between them as a driving force.
A fuel gas supply unit that supplies the fuel gas to the second space,
Partial oxidation reforming in the second space so that the oxygen partial pressure of the reforming gas discharged from the second space is within a predetermined range of the lower limit value Pmin or more and the upper limit value Pmax or less. A control unit that controls the reaction amount of the reaction and
Equipped with a,
The control unit controls the reaction amount of the partial oxidation reforming reaction in the second space by controlling the supply amount of the fuel gas to the second space by the fuel gas supply unit.
The lower limit value Pmin is 1 × ^10-23 (atm) at 1000 ° C.
The reformer , wherein the upper limit value Pmax is 1 × 10 ^-17 (atm) at 1000 ° C. In the reformer according to claim 1,
The upper limit value Pmax is equal to or higher than the first reference value in which the hydrogen selectivity (%), which is the ratio of the volume ratio of hydrogen to the total of the volume ratio of hydrogen in the reforming gas and the volume ratio of water, is set in advance. The carbon monoxide selectivity (%), which is the ratio of the volume ratio of carbon monoxide to the total of the volume ratio of carbon monoxide and the volume ratio of carbon dioxide in the reformed gas, is the first condition of A reforming apparatus, characterized in that the value is set so that at least one of a second condition of being equal to or higher than a preset second reference value is satisfied. In the reformer according to claim 2,
The reformer, wherein the first reference value is 95 (%). In the reformer according to claim 2,
The reformer, wherein the second reference value is 96 (%). In the reforming apparatus according to any one of claims 1 to 4.
The lower limit value Pmin is the amount of hydrocarbon consumed, which is the difference between the amount of hydrocarbon input and the amount of hydrocarbon contained in the reformed gas with respect to the amount of hydrocarbon input, which is the amount of hydrocarbon contained in the fuel gas. The reforming apparatus, characterized in that the hydrocarbon conversion rate (%), which is the ratio of the above, is a value set so as to satisfy the third condition that the hydrocarbon conversion rate (%) is equal to or higher than a preset third reference value. .. In the reformer according to claim 5,
The reformer, wherein the third reference value is 75 (%). In the reforming apparatus according to any one of claims 1 to 6 .
The lower limit value Pmin is 1 × ^10-22 (atm) at 1000 ° C.
The reformer, wherein the upper limit value Pmax is 1 × 10 ^-19 (atm) at 1000 ° C. In the reforming apparatus according to any one of claims 1 to 7 .
A reformer characterized in that the volume ratio (%) of methane to the total amount of hydrocarbons in the fuel gas is 50 (%) or more. In the reformer according to any one of claims 1 to 8 , further
A reformer comprising an oxygen sensor for measuring the oxygen partial pressure of the reforming gas discharged from the second space. In the reformer according to claim 9 ,
The oxygen sensor is a reformer that measures the oxygen partial pressure of the reforming gas based on the electromotive force generated in zirconia, which is an oxide ion conductor. In the reforming apparatus according to any one of claims 1 to 10 .
The control unit performs partial oxidation modification in the second space so that the total volume ratio (%) of hydrogen, carbon monoxide, and hydrocarbon in the reformed gas is 95 (%) or more. A reformer characterized by controlling the reaction amount of a quality reaction. In the reforming apparatus according to any one of claims 1 to 11 .
The control unit uses the second control unit so that the ratio of the volume ratio (%) of hydrogen to the volume ratio (%) of carbon monoxide in the reformed gas is 1.9 or more and 2.1 or less. A reforming apparatus characterized in that the reaction amount of a partial oxidation reforming reaction in a space is controlled. In the reforming apparatus according to any one of claims 1 to 12 .
A reformer characterized in that the hydrocarbon in the fuel gas is methane.

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