JP4385456B2 - High temperature shift converter for hydrogen production and operation method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a high-temperature shift converter for producing hydrogen used for producing high-purity hydrogen from a reformed gas after reforming a hydrocarbon such as natural gas or methanol, and an operating method thereof.
[0002]
[Prior art]
As a conventional technique for purifying high-purity hydrogen from a hydrogen-rich gas obtained by steam reforming natural gas, PSA (Pressure Swing Adsorption) has become industrially main. This PSA is a method of separating and purifying the target gas by changing the pressure of the hydrogen-rich gas introduced into the absorption tower and repeating adsorption and desorption on the adsorbent. The adsorbent includes a carbon molecular sieve. Synthetic zeolite is used according to the gas to be separated, and the target gas separation is performed by utilizing the different properties of the gas adsorbed on these adsorbents. The higher the pressure, the more adsorbed the unit adsorbent. On the contrary, the lower the pressure, the smaller the amount of adsorption.
[0003]
However, in the case of the hydrogen production method using PSA, in the hydrogen production apparatus of 600 Nm ³ / Hr, it is necessary to install 3 to 4 absorption towers and installation of a discharge tank. It cannot be a compact and inexpensive facility for producing hydrogen, and therefore there is a difficulty in applying it to a system using hydrogen as fuel by installing it in a narrow space as a hydrogen production apparatus.
[0004]
Therefore, it is assumed that high-purity hydrogen can be produced with a compact configuration. As shown in FIG. 4, for example, the hydrogen-rich gas obtained by steam reforming natural gas NG in the reformer 1 is heated to a high temperature. There has been proposed a hydrogen production apparatus in which the shift converter 2 separates only hydrogen and simultaneously causes a shift reaction.
[0005]
That is, the reforming chamber 3 filled with the reforming catalyst 4 and flowing the natural gas NG, and the heating chamber 5 filled with alumina balls and filled with the combustion gas 16 as the heat transfer promoting filling 6 In addition to the plate type reformer 1 formed by laminating a metal partition wall 7, a cooling chamber 10 filled with an alumina ball as a heat transfer promoting filler 9 on one side with a metal partition wall 8 interposed therebetween. And a shift reaction chamber 12 filled with a high temperature shift catalyst 11 on the opposite side of the partition wall 8 to cause a shift reaction, and a plate-type hydrogen gas chamber 13 having a flow path formed by irregularities, A palladium membrane or a palladium alloy membrane (hereinafter referred to as a palladium membrane) 14 is formed on the porous plate as a hydrogen permeable membrane for allowing only hydrogen to selectively pass between the gas chamber 13 and the shift reaction chamber 12. Cote on one side Whether or plating partition 15 comprising for packaging, palladium film 14 is a structure in which a high-temperature shift converter 2 of the plate type formed by laminating as the shift reaction chamber 12 side. When the palladium membrane 14 is used as the hydrogen permeable membrane, the palladium membrane 14 becomes brittle at 300 ° C. or less in the presence of hydrogen, so that the use temperature is set to 300 to 500 ° C.
[0006]
Natural gas NG is introduced into the cooling chamber 10 of the high-temperature shift converter 2 from the natural gas line 17 so as to be used for cooling during the shift reaction that is an exothermic reaction, and the natural gas NG exiting the cooling chamber 10 is used. Is introduced into the reforming chamber 3 of the reformer 1 through the natural gas line 17 and reformed, and the hydrogen-rich reformed gas reformed in the reforming chamber 3 of the reformer 1 The RG is led from the reformed gas line 18 to the heat exchanger 19 and adjusted to 300 to 500 ° C., which is the operating temperature of the high temperature shift converter 2 (use temperature of the catalyst 11), and then the shift reaction chamber 12 of the high temperature shift converter 2. In this case, a shift reaction is performed by an exothermic reaction, and the temperature is raised by reaction heat. However, the temperature is cooled by the cooling chamber 10 so that the outlet gas temperature becomes the maximum operating temperature of the high temperature shift catalyst. Reference numeral 27 denotes water vapor.
[0007]
In the proposed hydrogen production facility, pure hydrogen can be easily produced with the plate-type high-temperature shift converter 2 and the reformer 1, and the high-temperature shift converter 2 and the reformer 1 are small as a hydrogen production apparatus. It can be installed in a space.
[0008]
[Problems to be solved by the invention]
However, in the high temperature shift converter 2, the cooling chamber 10 is provided on one side in order to suppress the temperature rise due to the reaction heat, and therefore there is a problem that the hydrogen gas chambers 13 cannot be arranged on both sides of the shift reaction chamber 12. .
[0009]
Therefore, the present invention suppresses an increase in the gas temperature due to reaction heat so that the outlet gas temperature can be set to the maximum operating temperature of the high temperature shift catalyst without placing a cooling chamber on one side of the shift reaction chamber. A high-temperature shift converter for producing hydrogen and an operation method thereof are provided.
[0010]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention provides a porous plate coated with a hydrogen permeable membrane on both sides of a shift reaction chamber filled with a high temperature shift catalyst and subjected to a shift reaction by flowing a reformed gas. A structure in which the partition walls formed by plating are arranged so as to sandwich the shift reaction chamber, and plate-type hydrogen gas chambers are laminated on the outside thereof so that the reformed gas can flow into the shift reaction chamber. A high temperature shift converter for hydrogen production having
[0011]
Since the shift reaction chamber is sandwiched between the hydrogen gas chambers from both sides, the hydrogen production efficiency can be increased by allowing hydrogen to be taken out from both sides.
[0012]
In addition, a plate-type hydrogen gas chamber is laminated on both sides of a shift reaction chamber filled with a high-temperature shift catalyst so that the reformed gas flows and through a partition wall formed by coating or plating a porous plate with a hydrogen permeable membrane. In the high-temperature shift converter for hydrogen production, the thickness and area of the hydrogen permeable membrane of the partition wall are set, and the composition, flow rate, and pressure of the reformed gas are set, and the inlet gas temperature of the shift reaction chamber is assumed. After that, the shift reaction and the calculation considering the hydrogen permeation amount are performed to analyze the outlet gas temperature of the shift reaction chamber, and the inlet gas is adjusted so that the outlet gas temperature becomes about the maximum operating temperature of the high temperature shift catalyst by the reaction heat. The shift reaction chamber is calculated by calculating the temperature of the shift reaction chamber to obtain the inlet gas temperature of the shift reaction chamber, and allowing the reformed gas to flow into the shift reaction chamber at the determined inlet gas temperature. Without place cooling chamber on one side, by suppressing the gas temperature rises so the outlet gas temperature can be set to about the maximum operating temperature of the high-temperature shift catalyst by reaction heat.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0014]
FIG. 1 shows an embodiment of a hydrogen production apparatus incorporating a high-temperature shift converter 20 that is a feature of the present invention. Like the hydrogen production apparatus shown in FIG. The hydrogen-rich reformed gas RG obtained by reforming is subjected to a shift reaction by the high-temperature shift converter 20, and then only hydrogen is separated.
[0015]
As shown in FIG. 1, a plate type high temperature shift converter 20 of the present invention has a palladium film or a palladium alloy film (hereinafter referred to as a palladium film) as a hydrogen permeable film on both sides of a shift reaction chamber 12 filled with a high temperature shift catalyst 11. The partition 15 formed by coating or plating 14 on one side of the porous plate is arranged so as to sandwich the shift reaction chamber 12, and the plate-type hydrogen gas chambers 13 are laminated on the outside thereof. In order to operate this high-temperature shift converter 20 to obtain hydrogen, in addition to the reformer 1 and the heat exchanger 19 having the same configuration as shown in FIG. After the combustor 24 and the waste heat recovery boiler 25 are installed, the natural gas NG is boosted by the natural gas supply blower 21 and introduced into the heat exchanger 19 through the natural gas line 17. The hydrogen-rich reformed gas RG reformed in the reforming chamber 3 of the reformer 1 is introduced into the reforming chamber 3 of the reformer 1 from the reformed gas line 18 to the heat exchanger. The temperature is lowered through 19 and then introduced into the shift reaction chamber 12 of the high-temperature shift converter 20, and hydrogen generated by the shift reaction in the shift reaction chamber 12 is passed through the porous partition wall 15 having the palladium film 14 on the both sides. Each hydrogen gas chamber 13 is permeated so that high-purity hydrogen can be obtained from each hydrogen gas chamber 13. The air preheater 23 is preheated by introducing the air A compressed by the air blower 22 and then introduced into the combustor 24 where the remaining reformed hydrogen separated in the shift reaction chamber 12. Combusting together with the gas RG, the combustion gas 16 is supplied to the heating chamber 5 of the reformer 1 to be used as a heat source for the reforming reaction due to the endothermic heat generated in the reforming chamber 3. The combustion gas 16 exiting the chamber 5 is guided to the air preheater 23 and the waste heat recovery boiler 25 and then released to the atmosphere. On the other hand, the water W is sent to the waste heat recovery boiler 25 by the pump 26 to be steam 27. The obtained steam 27 is mixed with the natural gas NG in the natural gas line 17 to perform steam reforming.
[0016]
The high temperature shift converter 20 according to the present invention obtains an inlet gas temperature at which the gas temperature rises due to reaction heat to about 500 ° C., which is the maximum use temperature of the high temperature shift catalyst 11, in the shift reaction chamber 12. The reformed gas is introduced into the shift reaction chamber 12 at the inlet gas temperature and operated. For this purpose, the inlet gas temperature is obtained as follows. First, the thickness and area of the palladium membrane 14 as the hydrogen permeable membrane are set, the composition, flow rate, and pressure of the reformed gas RG are set, and the inlet gas temperature of the shift reaction chamber 12 is assumed. The outlet gas temperature of the shift reaction chamber 12 is analyzed by performing a calculation considering the shift reaction and the hydrogen permeation amount, and the inlet gas temperature is about the maximum operating temperature (500 ° C.) of the high temperature shift catalyst 11. A calculation for changing the gas temperature is performed to obtain the inlet gas temperature of the shift reaction chamber 12. When the inlet gas temperature of the shift reaction chamber 12 is obtained in this way, the reformed gas RG is caused to flow into the shift reaction chamber 12 at the obtained inlet gas temperature.
[0017]
The hydrogen permeation amount is
Q = Aexp (−B / RT) (1 / t) A ₁ (√ (P ₁ ) −√ (P ₂ ))
Here, Q: hydrogen permeation amount A, B: constant R: gas constant T: temperature t: film thickness A ₁ : area P ₁ : raw material side hydrogen partial pressure P ₂ : permeation side hydrogen partial pressure.
[0018]
For example, when the outlet gas temperature of the shift reaction chamber 12 is set to 500 ° C., control is performed so that the inlet gas temperature is set to 400 ° C. by looking at the increase in gas temperature due to reaction heat. In this case, the temperature condition of each part is as shown in FIG. 2, and the natural gas NG at 20 ° C. is boosted by the natural gas supply blower 21 to be raised to 157 ° C. By making it a mixed gas, it is introduced into the heat exchanger 19 at 152 ° C., heated to 487 ° C., and then supplied to the reforming chamber 3 of the reformer 1. In the reforming chamber 3, heat of the combustion gas 16 at 750 ° C. introduced into the heating chamber 5 is transferred from the partition wall 7,
CH ₄ + H ₂ O → CO + 3H ₂
These reactions are performed to produce carbon monoxide and hydrogen. Although the temperature of the reformed gas RG is about 720 ° C., the operating temperature of the high temperature shift converter 20 is 300 to 500 ° C., so that the reformed gas RG is cooled to about 400 ° C. by the heat exchanger 19. The reformed gas RG is introduced into the shift reaction chamber 12 at that temperature. The operating temperature range of the palladium membrane 14 as the hydrogen permeable membrane is 300 to 500 ° C. as described above. However, since it matches the operating temperature of the high temperature shift converter 20, the high temperature shift converter 20 is at the original operating temperature. It can be operated and the palladium membrane 14 is not deteriorated. In the shift reaction chamber 12, due to the exothermic reaction,
CO + H ₂ O → CO ₂ + H ₂
In this reaction, carbon monoxide is removed and carbon dioxide and hydrogen are obtained. At the same time, only the hydrogen film is separated using the palladium film 14 on the surface of the partition wall 15 and passes through the porous plate to obtain high purity. Hydrogen H ₂ flows out into the hydrogen gas chamber 13.
[0019]
The remaining reformed gas separated by hydrogen in the shift reaction chamber 12 of the high temperature shift converter 20 is discharged at a set temperature of 500 ° C. At this time, the reformed gas contains part of CO that has not undergone the shift reaction and partly unreformed CH ₄ in addition to H ₂ . It will be used as a heat source.
[0020]
Incidentally, the principle that only hydrogen generated by the shift reaction in the shift reaction chamber 12 is separated through the palladium membrane 14 is as follows.
[0021]
(1) Hydrogen molecules are adsorbed on the palladium membrane.
(2) Adsorbed hydrogen molecules dissociate into hydrogen atoms.
(3) Hydrogen atoms are ionized and separated into protons and electrons.
(4) Proton diffuses from the front surface to the back surface of palladium.
(5) Protons reaching the back surface recombine with electrons on the palladium film surface to form hydrogen atoms.
(6) Hydrogen atoms are combined to form hydrogen molecules.
(7) Hydrogen molecules are detached from the palladium membrane.
[0022]
Thus, only hydrogen that can be in a proton state permeates the palladium membrane 14, and impurities that cannot be in such a state do not permeate the palladium membrane 14, so that high-purity hydrogen can be purified. .
[0023]
In the present invention, the inlet gas temperature is determined so that the outlet gas temperature of the shift reaction chamber 12 of the high temperature shift converter 20 is about the maximum operating temperature of the high temperature shift catalyst 11, and the reformed gas RG is supplied to the shift reaction chamber 12 at that temperature. 4, it is not necessary to install the cooling chamber 10 as shown in FIG. 4 on one side of the shift reaction chamber 12. Accordingly, the hydrogen gas chambers 13 are arranged on both sides of the shift reaction chamber 12. Thus, hydrogen separation efficiency can be increased and hydrogen can be produced efficiently.
[0024]
Next, FIG. 3 shows another embodiment of the present invention. Instead of the reformer 1, the cooling for cooling the reformed gas RG in addition to the reforming chamber 30 and the heating chamber 31 is provided. Using a reformer 29 provided with a chamber (heat exchange chamber) 32, natural gas NG is heated through the heat exchange chamber 19 by the natural gas line 17 and then introduced into the reforming chamber 30 of the reformer 29. Then, the reformed gas RG reformed in the reforming chamber 30 of the reformer 29 is cooled in the cooling chamber 32 and then introduced into the shift reaction chamber 12 of the high temperature shift converter 20 so that hydrogen permeation and shift reaction are performed. The reformed gas that has not been permeated is combusted by the combustor 24 and introduced into the heating chamber 31 of the reformer 29 to be used as a heat source for the reforming reaction. The gas is mixed with natural gas NG and water vapor 27 and heat in the heat exchanger 19. After conversion, in which the used to preheat the air A through the air preheater 23, and so as to be used as the heat source of the water vapor generated by the waste heat recovery boiler 25. In addition, the same code | symbol is attached | subjected to the same part as FIG.
[0025]
Also when the high temperature shift converter 20 is operated in the hydrogen production apparatus shown in FIG. 3, a cooling chamber is placed on one side of the shift reaction chamber 12 of the high temperature shift converter 20 by performing the same operation method as shown in FIG. 1. Even if it is not, it is possible to suppress the gas temperature from rising due to the reaction heat and to set the outlet gas temperature to the maximum operating temperature of the high temperature shift catalyst 11.
[0026]
【The invention's effect】
As described above, according to the high temperature shift converter for hydrogen production of the present invention, the hydrogen permeable membrane is provided on both sides of the shift reaction chamber filled with the high temperature shift catalyst and allowed to flow the reformed gas to perform the shift reaction. A partition formed by coating or plating the porous plate is arranged so as to sandwich the shift reaction chamber, and a plate-type hydrogen gas chamber is laminated on the outside thereof, and the reformed gas is introduced into the shift reaction chamber. Since it is configured to flow in, a cooling chamber that has been conventionally disposed on one side of the shift reaction chamber can be eliminated, and hydrogen gas chambers can be stacked on both sides of the shift reaction chamber, In addition to being able to be compact, it is possible to increase the efficiency of separating and taking out hydrogen, and when determining the inlet gas temperature from the outlet gas temperature of the shift reaction chamber, first, the thickness and area of the hydrogen permeable membrane As well as setting the reforming gas composition, flow rate, and pressure, assuming the gas temperature at the inlet of the shift reaction chamber, and then calculating the shift reaction chamber by calculating the shift reaction and hydrogen permeation amount. Analyze the outlet gas temperature, and calculate the inlet gas temperature in the shift reaction chamber by calculating the inlet gas temperature so that the outlet gas temperature is about the maximum operating temperature of the high temperature shift catalyst by the reaction heat. By allowing the reformed gas to flow into the shift reaction chamber at the inlet gas temperature, it is possible to prevent the gas temperature from rising due to the reaction heat without placing a cooling chamber on one side of the shift reaction chamber, An excellent effect that the outlet gas temperature can be set to the maximum operating temperature of the high temperature shift catalyst is exhibited.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a hydrogen production apparatus showing an embodiment of a high temperature shift converter for producing hydrogen according to the present invention.
2 is an example diagram showing a temperature state of each part when operating a high-temperature shift converter in the hydrogen production apparatus of FIG. 1; FIG.
FIG. 3 is a schematic diagram showing another embodiment of the present invention.
FIG. 4 is a schematic diagram showing an example of a hydrogen production apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Reformer 11 High temperature shift catalyst 12 Shift reaction chamber 13 Hydrogen gas chamber 14 Palladium membrane (hydrogen permeable membrane)
15 Partition 20 High-temperature shift converter 29 Reformer NG Natural gas RG Reformed gas

Claims (2)

A partition formed by coating or plating a porous plate with a hydrogen permeable membrane is sandwiched between both sides of a shift reaction chamber in which a high temperature shift catalyst is filled and a reforming gas is allowed to flow to cause a shift reaction. A high-temperature shift converter for producing hydrogen, characterized in that a plate-type hydrogen gas chamber is laminated on the outside of the gas chamber and a reformed gas is allowed to flow into the shift reaction chamber. A plate-type hydrogen gas chamber is laminated on both sides of a shift reaction chamber filled with a high temperature shift catalyst so that the reformed gas flows and through a partition formed by coating or plating a porous plate with a hydrogen permeable membrane. In the high-temperature shift converter for hydrogen production, the thickness and area of the hydrogen permeable membrane of the partition wall are set, and the composition, flow rate, and pressure of the reformed gas are set, and the inlet gas temperature of the shift reaction chamber is assumed. After that, the shift reaction and the hydrogen gas permeation calculation are performed to analyze the shift reaction chamber outlet gas temperature, and the reaction gas is used to adjust the inlet gas temperature so that the outlet gas temperature is about the maximum operating temperature of the high temperature shift catalyst. A calculation for changing is performed to determine the inlet gas temperature of the shift reaction chamber, and the reformed gas is allowed to flow into the shift reaction chamber at the determined inlet gas temperature. Method of operating the shift converter.

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