JP4204291B2 - Reformer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a reforming unit that generates reformed gas from fuel and water vapor, a shift unit that reacts carbon monoxide contained in the reformed gas with water vapor to convert it into carbon dioxide gas and hydrogen gas, and a shift unit. It is related with the reformer provided with the CO purification part which reacts with the air the carbon monoxide gas which remains in the reformed gas which passed through, and oxidizes to carbon dioxide gas.
[0002]
[Prior art]
A reforming section that generates a hydrogen-rich reformed gas by reacting fuel and reformed water with a steam reforming reaction; a shift section that reacts and reduces the carbon monoxide gas contained in the reformed gas with steam; and The reforming water evaporates in a reforming apparatus including a CO purifying unit that oxidizes carbon monoxide gas remaining in the reformed gas that has passed through the shift unit with air, and a combustion unit that supplies combustion gas to the reforming unit. The gas is vaporized into the gas-liquid mixed steam by the combustion gas supplied from the combustion section in the cooler, and after the gas-liquid mixed steam cools the CO purifying section, the heat is exchanged with the reformed gas and heated. Japanese Patent Application Laid-Open No. 2001-163601 describes a reformer supplied to the section.
[0003]
[Patent Document 1]
Japanese Patent Laying-Open No. 2001-163601 (pages 3, 4 and FIG. 4)
[0004]
[Problems to be solved by the invention]
In the above conventional reformer, the gas-liquid mixed steam that has cooled the CO purification section exchanges heat with the reformed gas, and the reformed gas is cooled to the activation temperature range of the shift section catalyst and supplied to the shift section. In addition, since the heat balance is not taken so that the steam is heated to the reforming section activation temperature range and supplied to the reforming section, the combustion gas temperature-controlled with water is supplied to the shifting section. Had to adjust the temperature. In addition, since the fuel is supplied to the reforming unit separately from the steam, the fuel must be heated by the combustion gas without being heated by the reformed gas, and there is a problem that the heat energy is not efficiently used. It was.
[0005]
The present invention has been made in order to solve the conventional problems, and the temperature of the reformed gas in the CO purification unit, the temperature of the reformed gas flowing into the shift unit, and the temperature of the steam supplied to the reforming unit are The heat exchange is performed between the reformed gas and the steam in a state where the heat balance of the entire apparatus is taken so as to be in the active temperature range of each catalyst.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the structural feature of the invention according to claim 1 is that the reforming water is evaporated to gas-liquid mixed water vapor and heated to the activation temperature range by the combustion gas generated in the combustion section. Heat exchange between the reformed part that reforms fuel and steam into reformed gas by the reformed part catalyst, the reformed gas generated in the reformed part and the gas-liquid mixed steam, A main heat exchanger that cools the reformed gas to the active temperature region of the shift unit catalyst and supplies the gas to the shift unit, heats the steam to the active temperature region of the reformer unit catalyst, and supplies the steam to the reforming unit; The shift unit converts carbon monoxide gas and water vapor contained in the reformed gas cooled by the main heat exchanger into hydrogen gas and carbon dioxide gas by the shift unit catalyst, and the reformed gas derived from the shift unit Carbon monoxide gas contained in the catalyst is reacted with air by a CO purification unit catalyst to produce carbon dioxide. A temperature of the reformed gas that is connected between the evaporator and the main heat exchanger and that flows between the CO purifying unit by the gas-liquid mixed water vapor and that is an active temperature of the CO purifying unit catalyst. A CO purification section heat exchanger that lowers the temperature to the region.
[0007]
  The structural features of the invention according to claim 2 are: an evaporator for evaporating the reformed water into gas-liquid mixed steam; a mixing section for mixing fuel with the gas-liquid mixed steam generated by the evaporator; and a combustion section A reforming section for reforming fuel and water vapor into a reformed gas by a reforming catalyst heated to an activation temperature range by the combustion gas generated in step 1, and the reformed gas generated in the reforming section and the mixing section Heat-exchanged with the gas-liquid mixed steam mixed with the fuel in the step, the reformed gas is cooled to the active temperature range of the shift section catalyst and supplied to the shift section, and the mixed steam and fuel are modified. A main heat exchanger that is heated to an active temperature range of the mass catalyst and supplied to the reforming section, and a carbon monoxide gas and water vapor contained in the reformed gas cooled by the main heat exchanger are shifted to the shift section catalyst. A shift unit that converts the gas into hydrogen gas and carbon dioxide gas, and a modification derived from the shift unit. The carbon monoxide gas contained in the gas is reacted with air by CO purification unit catalyst and CO purification unit to the carbon dioxide gas, between the main heat exchanger and the evaporatorBefore or after the mixing sectionA CO purification unit heat exchanger is provided which is connected and reduces the temperature of the reformed gas flowing through the CO purification unit by the gas-liquid mixed water vapor to the activation temperature range of the CO purification unit catalyst.
[0008]
    The structural feature of the invention according to claim 3 is that in claim 2, the main heat exchanger isGas-liquid mixed steamOf the inlet and the CO purification section heat exchangerGas-liquid mixed steamAnd close the outletGas-liquid mixed steamThe mixing portion is provided between the inflow port and the outflow port.
[0009]
The structural feature of the invention according to claim 4 is that in any one of claims 1 to 3, the measuring device for measuring the temperature of the shift unit, and the temperature of the shift unit measured by the measuring device is a low threshold. When the temperature is lower than the value, the amount of reforming water is decreased, the amount of air supplied to the CO purification unit is increased, and when the temperature of the shift unit is higher than a high temperature threshold, the amount of reforming water is increased and the CO purification is performed. A control device for increasing the amount of air supplied to the unit.
[0010]
A structural feature of the invention according to claim 5 is that, in claim 4, the control device reduces the amount of the reformed water when the temperature of the shift unit is lower than a low temperature threshold, and causes the CO purification unit to Even if the amount of air supplied is increased, the amount of reforming water is increased when the temperature of the shift unit falls below a lower limit value or when the temperature of the shift unit is higher than a high temperature threshold, and the CO purification unit If the temperature of the shift part rises above the upper limit value even if the amount of air supplied to is increased, an abnormality treatment is performed.
[0011]
[Operation and effect of the invention]
In the invention according to claim 1 configured as described above, the reforming section catalyst is heated to the active temperature range by the combustion gas generated in the combustion section, and the fuel and the steam are reformed into the reformed gas. The reformed gas generated in the reforming section exchanges heat with the gas-liquid mixed steam generated in the evaporator in the main heat exchanger, and the reformed gas is cooled to the activation temperature range of the shift section catalyst and is transferred to the shift section. Then, the steam is heated to the activation temperature range of the reforming part catalyst and supplied to the reforming part. Carbon monoxide gas and water vapor contained in the cooled reformed gas are converted into hydrogen gas and carbon dioxide gas by the catalyst in the shift section. Carbon monoxide gas contained in the reformed gas derived from the shift unit reacts with air by the catalyst in the CO purification unit and is oxidized to carbon dioxide. The temperature of the reformed gas flowing through the CO purification unit is lowered to the activation temperature range of the CO purification unit catalyst by the gas-liquid mixed steam in the CO purification unit heat exchanger connected between the evaporator and the main heat exchanger. .
[0012]
In this way, the temperature of the reformed gas in the CO purifying unit, the temperature of the reformed gas flowing into the shift unit, and the temperature of the steam supplied to the reforming unit are circulated by circulating the steam in a heat balanced state. It is possible to control the activation temperature range of the catalyst in each part, to reduce the heat energy discharged to the outside, and to provide a reformer with high reforming efficiency. In addition, it is not necessary to divert and supply the reforming water to the heat exchanger for controlling the temperature of the shift unit, so that the necessary pumps, valves, etc. are no longer required and the power is reduced and the efficiency is improved. Equipment costs can be reduced by reducing the number of auxiliary equipment. Furthermore, the reformed gas flowing through the CO purifying section is boiled and cooled with gas-liquid mixed steam, whereby the temperature of the reformed gas can be kept well in the active temperature range of the CO purifying section catalyst whose temperature control is severe.
[0013]
In the invention which concerns on Claim 2 comprised as mentioned above, a fuel is mixed with the gas-liquid mixing water vapor | steam produced | generated with the evaporator. The combustion gas generated in the combustion section heats the catalyst in the reforming section to the active temperature range, and the fuel and water vapor are reformed into the reformed gas. The reformed gas generated in the reforming section exchanges heat with the gas-liquid steam mixed with fuel in the main heat exchanger, and the reformed gas is cooled to the activation temperature range of the shift section catalyst and supplied to the shift section. The steam mixed with the fuel is heated to the activation temperature range of the reforming section catalyst and supplied to the reforming section. Carbon monoxide gas and water vapor contained in the cooled reformed gas are converted into hydrogen gas and carbon dioxide gas by the catalyst in the shift section. Carbon monoxide gas contained in the reformed gas derived from the shift unit reacts with air by the catalyst in the CO purification unit and is oxidized to carbon dioxide. The temperature of the reformed gas flowing through the CO purification unit is lowered to the activation temperature range of the CO purification unit catalyst by the gas-liquid mixed steam in the CO purification unit heat exchanger connected between the evaporator and the main heat exchanger. . Thereby, in addition to the effect of the invention of claim 1, the fuel is heated to the activation temperature region of the reforming catalyst by the reformed gas together with the steam and is supplied to the reforming section, so that the thermal energy can be made more effective. It can be used to improve the reforming efficiency.
[0014]
  In the invention according to claim 3 configured as described above, the main heat exchangerGas-liquid mixed steamInlet and CO purification section heat exchangerGas-liquid mixed steamAnd close the outletGas-liquid mixed steamSince the fuel is mixed with the gas-liquid mixed steam between the inlet and the outlet, the gas-liquid mixed steam accurately controls the temperature of the CO purification section and then the main heat from the CO purification section heat exchanger without cooling. It can flow into the exchanger.
[0015]
In the invention according to claim 4 configured as described above, when the temperature of the shift unit measured by the measuring device is lower than the low temperature threshold, the amount of reformed water is reduced and the amount of air supplied to the CO purification unit is reduced. To increase. When the temperature is higher than the high temperature threshold, the amount of reforming water is increased and the amount of air supplied to the CO purification unit is increased. Thereby, even when the heat balance is slightly lost, the temperatures of the CO purification unit, the shift unit, and the reforming unit can be maintained within the activation temperature range of each catalyst.
[0016]
In the invention which concerns on Claim 5 comprised as mentioned above, when the temperature of the shift part measured by the measuring apparatus is lower than a low temperature threshold value, the amount of reforming water is decreased, and the air quantity supplied to the CO purification part Even when the temperature of the shift unit falls below the lower limit even when the value is increased, or when the temperature of the shift unit is higher than the high temperature threshold, the amount of reforming water is increased and the amount of air supplied to the CO purification unit is increased. However, if the temperature of the shift section rises above the upper limit value, abnormal treatment is performed, preventing the operation from being continued in a state where the heat balance is lost and the reformed gas deviates from the activation temperature range of each catalyst. can do.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the reformer according to the present invention will be described. FIG. 1 is a schematic diagram showing an outline of a fuel cell system using the reformer 20. This fuel cell system includes a fuel cell 10 and a reformer 20 that generates a hydrogen-rich reformed gas having a very low carbon monoxide concentration necessary for the fuel cell 10. The reformer 20 includes a reforming unit 30 that generates a hydrogen-rich reformed gas by performing a steam reforming reaction between city gas, LPG, kerosene, and other fuel and steam, and carbon monoxide gas contained in the reformed gas. The carbon monoxide is subjected to a carbon monoxide shift reaction, and a shift unit 40 and a CO purification unit 60 that selectively oxidizes carbon monoxide contained in the reformed gas derived from the shift unit 40 to further reduce the carbon monoxide. . That is, in the reforming unit 30, the supplied fuel and water vapor react with each other by the catalyst to generate hydrogen-rich reformed gas. The reforming section catalyst 31a filled in the reaction chamber 31 of the reforming section 30 is activated by the combustion gas supplied from the combustion section 36 to activate the reforming section catalyst 31a that promotes the reaction in the reforming section 30 (see FIG. 550-700 ° C). The carbon monoxide gas contained in the reformed gas derived from the reforming unit 30 reacts with water vapor by the shift unit catalyst 40a in the shift unit 40 to be converted into hydrogen gas and carbon dioxide gas. The high-temperature reformed gas flowing out from the reforming unit 30 is lowered by the main heat exchanger 34 to the activation temperature range (200 to 300 ° C.) of the shift unit catalyst 40a that promotes the carbon monoxide shift reaction in the shift unit 40. The The carbon monoxide gas contained in the reformed gas derived from the shift unit 40 reacts with oxygen in the air by the CO purification unit catalyst 60a in the CO purification unit 60 and is oxidized to carbon dioxide. The reformed gas flowing through the CO purification unit 60 is lowered to the activation temperature range (100 to 200 ° C.) of the CO purification unit catalyst 60 a by the CO purification unit heat exchanger 70 provided in the CO purification unit 60. The fuel cell 10 supplied with the reformed gas generated by the reformer 20 generates electric power by reaction of hydrogen gas and oxygen gas of the reformed gas. In addition, the fuel used in this Embodiment is city gas (Methane gas is the main component).
[0018]
The reforming unit 30 includes a reaction chamber 31 filled with a reforming unit catalyst 31 a that promotes a reforming reaction, and a heating chamber 32 that is provided in close contact with the reaction chamber 31 and heats the reaction chamber 31. The combustion chamber 32 is supplied with the combustion gas generated in the combustion section 36 to heat the reforming section catalyst 31a to the activation temperature range (550 to 700 ° C.). The reforming section catalyst 31a filled in the reaction chamber 31 is a granular material having a substantially constant size, and is formed by, for example, supporting a metal such as ruthenium or nickel on a ceramic sphere. The combustion unit 36 includes a burner 33 that is supplied with combustion fuel, off-gas from the fuel cell 10, and combustion air, and supplies high-temperature combustion gas to the heating chamber 32.
[0019]
The reaction chamber 31 is supplied with steam mixed with fuel (methane gas) heated to the activation temperature region of the reforming part catalyst 31a, and the fuel reacts with the steam by the catalyst 31a as shown in the following chemical formula 1 and reforms. To produce hydrogen gas and carbon monoxide gas (so-called steam reforming reaction). At the same time, in the reaction chamber 31, as shown in the chemical formula 2 below, so-called carbon monoxide in which the carbon monoxide gas generated by the steam reforming reaction reacts with the steam and is converted into hydrogen gas and carbon dioxide gas. A shift reaction has occurred. The hydrogen-rich reformed gas is generated in the reforming unit 30 in this way.
[0020]
[Chemical 1]
CH₄+ H₂O → 3H₂+ CO
[0021]
[Chemical formula 2]
CO + H₂O → H₂+ CO₂
[0022]
Since the steam reforming reaction described above is an endothermic reaction, the reforming part catalyst 31a is heated by the burner 33. The burner 33 is connected to an off gas supply pipe 33 a connected to the fuel cell 10, and is supplied with hydrogen gas (off gas) that has not been used for the reaction in the fuel cell 10. Further, when necessary such as when the reformer is started, a combustion fuel supply pipe 33b connected to a fuel supply source is connected to supply combustion fuel. Further, the burner 33 is connected to a combustion air supply pipe 33c for supplying combustion air for burning the supplied off gas or combustion fuel. The off-gas or combustion fuel is burned in the burner 33 to generate high-temperature combustion gas. The combustion gas is supplied to the heating chamber 32 and the reaction chamber 31 is heated, so that the reforming catalyst 31a is activated. To be heated.
[0023]
The combustion gas in the heating chamber 32 is supplied to the evaporator 35 through the exhaust pipe 32a and then exhausted to the outside as exhaust gas. In the evaporator 35, the reformed water supplied from the water supply source through the water supply pipe 35b is heated by the high-temperature combustion gas supplied from the exhaust pipe 32a to become a gas-liquid mixed steam in a saturated state in which the gas and liquid are mixed. It leads to the water vapor supply pipe 35a. The water supply pipe 35 b is wound around the outer periphery of the heating chamber 32, and the water supplied from the water supply source is preheated by the heating chamber 32. The water vapor supply pipe 35a is connected to the inlet of the CO purification unit heat exchanger 70, and the gas-liquid mixed water vapor converts the temperature of the reformed gas flowing through the CO purification unit 60 to the CO purification unit catalyst 60a by the CO purification unit heat exchanger 70. Cool to the active temperature range. The outlet of the CO purification unit heat exchanger 70 is disposed close to the inlet of the main heat exchanger 34 provided between the reforming unit 30 and the shift unit 40, and connects the outlet and the inlet. A fuel supply pipe 37 is connected to the steam supply pipe 35 a that is connected by a mixing unit 71, and fuel is mixed with the gas-liquid mixed steam generated by the evaporator 35. The main heat exchanger 34 exchanges heat between the reformed gas generated in the reforming unit 30 and the gas-liquid mixed steam mixed with fuel in the mixing unit 71, and the high-temperature reformed gas is transferred to the shift unit catalyst 40a. After cooling to the active temperature range and supplying to the shift unit 40, the mixed steam and fuel are heated to the active temperature range of the reforming unit catalyst 31 a and supplied to the reaction chamber 31 of the reforming unit 30. In this case, the heating temperature of the gas-liquid mixed steam mixed with the fuel may be slightly lower than the activation temperature range of the reforming part catalyst 31a, and if heated to the activation temperature range of the reforming part catalyst 31a substantially. Good.
[0024]
The shift unit catalyst 40a filled in the shift unit 40 is a granular material having a substantially constant size made of an oxide such as copper or zinc, and is formed in a cylindrical shape. The catalyst 40a is converted into hydrogen gas and carbon dioxide gas by a carbon monoxide shift reaction (see Chemical Formula 3 below) of carbon monoxide and water vapor contained in the reformed gas introduced from the main heat exchanger 34. , Reduce the carbon monoxide concentration. This shift part catalyst 40a has an active temperature range of 200 to 300 ° C. and good thermal conductivity. The carbon monoxide shift reaction is an exothermic reaction.
[0025]
[Chemical 3]
CO + H₂O → H₂+ CO₂
[0026]
The reformed gas having a reduced carbon monoxide concentration derived from the shift unit 40 described above is supplied to the CO purification unit 60. The carbon monoxide remaining in the supplied reformed gas is oxidized into carbon dioxide by the action of the supplied CO oxidized air and the CO purification unit catalyst 60a as shown in the following chemical formula 4. The CO purification unit catalyst 60a is obtained by, for example, supporting platinum or the like on a support made of alumina, zirconia, or the like, and the activation temperature range is 100 to 200 ° C. A reformed gas having a carbon monoxide concentration of 10 ppm or less is derived from the CO purification unit 60, and a hydrogen-rich reformed gas having an extremely low carbon monoxide concentration is supplied to the fuel cell 10.
[0027]
[Formula 4]
CO + 1 / 2O₂ → CO₂
[0028]
The CO purification unit 60 is connected to the fuel electrode of the fuel cell 10 via the reformed gas supply pipe 61. The reformed gas supply pipe 61 is provided with a switching device 62 to which a bypass pipe 63 connected to an off-gas combustor (not shown) is connected. Is connected to the off-gas combustor, and the CO purification unit 60 is connected to the fuel cell 10 in a steady state. When the reformed gas and air are supplied to the fuel electrode and the air electrode, respectively, the fuel cell 10 generates a predetermined reaction to generate electric power. At this time, off-gas and water (gas) are derived from the fuel electrode and the air electrode of the fuel cell 10, respectively.
[0029]
Next, the operation of the above-described reformer 20 will be described. When the reformer 20 is started, the CO purifier 60 is connected to the off-gas combustor by the switching device 62 and combustion fuel is supplied to the burner 33 of the reformer 30 to be burned. Thereby, the catalyst 31a and the evaporator 35 in the reforming unit 30 are heated. When the evaporator 35 is heated to a predetermined temperature, the supply of reforming water to the evaporator 35 is started, and the gas-liquid mixed steam generated in the evaporator 35 is converted into the CO purification unit heat exchanger 70 and the main heat exchange. It is supplied to the reforming unit 30 via the vessel 34. Thereafter, the supply of fuel to the mixing unit 71 is started, and the steam reforming reaction and the carbon monoxide shift reaction described above occur in the reforming unit 30. The reformed gas derived from the reforming unit 30 is derived from the CO purifying unit 60 after the carbon monoxide gas is reduced by the shift unit 40 and the CO purifying unit 60. After that, when the carbon monoxide concentration in the derived reformed gas becomes a predetermined value or less, the CO purifier 60 is connected to the fuel cell 10 by the switching device 62, the start-up operation is terminated, and the steady operation is started. .
[0030]
During this steady operation, the heat reforming apparatus 20 as a whole is in a heat balance state, and as shown in FIG. 2, the gas-liquid mixed steam with a dryness of 0.6 generated by the evaporator 35 is subjected to CO purification. The reformed gas flowing through the CO purification unit 60 in the partial heat exchanger 70 is boiled and cooled from about 250 ° C. to about 100 ° C. to be steam having a dryness of 0.9. Since the gas-liquid mixed water vapor has a high condensation heat conductivity, the temperature of the reformed gas is accurately and well lowered to the activation temperature range of the CO purification unit catalyst 60a to oxidize the remaining carbon monoxide gas to oxidize the carbon dioxide gas. Can be.
[0031]
The gas-liquid mixed water vapor flowing out from the CO purification unit heat exchanger 70 and mixed with the fuel in the mixing unit 71 flows into the main heat exchanger 34 through the short water vapor pipe 35a with almost no heat energy. The gas-liquid mixed steam mixed with the fuel cools the reformed gas generated in the reforming section 30 in the main heat exchanger 34 from about 650 ° C. to about 200 ° C., and itself increases from about 100 ° C. to about 550 ° C. It is heated and supplied to the reforming unit 30. The reforming unit 30 is supplied with reaction heat from the reforming unit catalyst 31a in which the mixed fuel and water vapor are heated by the combustion gas to perform a steam reforming reaction, and a carbon monoxide shift reaction to perform a hydrogen rich reforming. Generate gas.
[0032]
The reformed gas cooled to about 200 ° C. by the main heat exchanger 34 and sent to the shift unit 40 is converted into carbon monoxide gas and water vapor contained in the reformed gas by the action of the catalyst 40a in the shift unit 40. It undergoes a carbon shift reaction and is transformed into hydrogen gas and carbon dioxide gas, and the temperature rises to about 250 ° C. The reformed gas that has been raised to about 250 ° C. by the shift unit 40 and sent to the CO purification unit 60 is cooled to about 100 ° C. by the CO purification unit heat exchanger 70 and reformed by the action of the catalyst 60a in the CO purification unit 60. The carbon monoxide gas contained in the gas reacts with the CO-oxidized air supplied to be oxidized to carbon dioxide gas, and a reformed gas having a carbon monoxide concentration of 10 ppm or less is derived from the CO purification unit 60, and this hydrogen rich A reformed gas is supplied to the fuel cell 10.
[0033]
An example of the heat balance of the reformed gas, the amount of heat received by the reforming water, and the amount of heat applied to the combustion gas when the reformer 20 is operated in a state where the heat balance is achieved as a whole is shown. The operating conditions of the reformer 20 are: city gas as fuel, 1.5 mol / min, reformed water, 5.13 mol / min (steam carbon ratio, 2.85), CO oxidant air, 9 NL / min, and city as combustion gas. This is the case where gas is supplied at 13 NL / min and the fuel cell 10 outputs 10 kW of electricity. The reformed gas has a heat balance in which the supplied fuel is reformed at a conversion rate of 85% and absorbs 4.4 kW, and the main heat exchanger 34 is cooled from 650 ° C. to 200 ° C. Dissipates 5 kW, shifts the content of carbon monoxide gas from 11% to 0.5% and dissipates 0.5 kW, and CO purifier 60 cools the outlet temperature to 100 ° C and dissipates 0.7 kW To do. The amount of heat received from the reformed water is heated from 100 ° C. to 550 ° C. in the main heat exchanger 34 to receive 2.3 kW, and the CO purification section heat exchanger 70 is boiled and cooled to receive 0.6 kW. Then, it receives 2.4kW. The amount of heat received from the reformed water until the start of boiling is 0.55 kW, the amount of heat received as latent heat of evaporation is 3.48 kW, and the amount of heat received from the end of boiling to 550 ° C. is 1.39 kW. The heating amount of the combustion gas is 5.1 kW when the temperature of the combustion gas is changed from 1000 ° C. to 580 ° C. in the reforming unit 30, and 2.65 kW is heated from 580 ° C. to 100 ° C. in the evaporator 35. The combustion gas at ℃ is exhausted and 1.25 kW is exhausted.
[0034]
Next, the control when the reformer 20 loses the heat balance as a whole will be described. Reference numeral 72 denotes a thermocouple attached to the shift unit 40 and functions as a measuring device for measuring the temperature of the shift unit 40. When the temperature of the shift unit 40 measured by the thermocouple 72 is between a low temperature threshold value, for example, 190 ° C. and a high temperature threshold value, for example, 280 ° C., the reformer 20 is in a heat balance state as a whole. Was confirmed by experiments. As shown in FIG. 3, when the temperature of the shift unit 40 falls below the low temperature threshold, the flow rate of the reforming water is reduced by about 10% to change the steam carbon ratio from 3 to 2.7, and the CO purification unit When the amount of CO oxidation air supplied to 60 is increased by about 20% and the ratio of oxygen to carbon monoxide is changed from 3 to 3.6, the temperature of the shift unit 40 rises and the heat balance of the reformer 20 is restored. This was empirically recognized and confirmed by experiments. As shown in FIG. 4, when the temperature of the shift unit 40 rises above the high temperature threshold, the flow rate of reforming water is increased by about 10% to change the steam carbon ratio from 3 to 3.3. If the amount of the oxidized CO air to be supplied is increased by about 20% and the ratio of oxygen to carbon monoxide is changed from 3 to 3.6, the temperature of the shift unit 40 decreases and the heat balance of the reformer 20 can be restored. It was recognized empirically and confirmed by experiments.
[0035]
The control device 73 takes in the temperature of the shift unit 40 from the thermocouple 72 and executes a program shown in FIGS. 5 and 6 to control the amount of reforming water and the amount of CO oxidized air in accordance with the temperature of the shift unit 40. 74 and 75 are controlled. In FIG. 5, when it is determined that the temperature Ts of the shift unit 40 is lower than the low temperature threshold TL1, for example, 190 ° C. (step 81), the flow rate control valve 74 is throttled to reduce the amount of reforming water by 10% ( Step 82), the amount of cooling in the main heat exchanger 34 is reduced. The flow rate control valve 75 is opened and CO oxidized air in anticipation that the parallel composition moves and the carbon monoxide concentration increases due to the decrease in the activity of the shift unit catalyst 42a due to the temperature decrease in the shift unit 40 and the decrease in the amount of water vapor. The amount is increased by 20% (step 83). It is determined whether or not the temperature Ts of the shift unit 40 has returned to the low temperature threshold TL1 or more (step 84). When the temperature Ts becomes equal to or higher than the low temperature threshold TL1, the amount of reforming water is returned to the rated value (step 85). Since the generation of water vapor is delayed, the amount of CO oxidized air remains increased for about 2 minutes, and after 2 minutes (step 86), the amount of CO oxidized air is returned to the rated value (step 87), and the steady operation state is reached. To. If the temperature Ts does not return to the low temperature threshold value TL1 or more, it is determined whether or not the temperature Ts has fallen below a lower limit value TL2, for example, 175 ° C. (step 88). Abnormal treatments such as stopping the supply of quality gas and turning on the alarm lamp are performed (step 89).
[0036]
In FIG. 6, when it is determined that the temperature Ts of the shift unit 40 is higher than the high temperature threshold TH1, for example, 280 ° C. (step 91), the flow control valve 74 is opened to increase the amount of reforming water by 10% ( Step 92) The cooling amount in the main heat exchanger 34 is increased. Assuming that the equilibrium composition moves and the carbon monoxide concentration increases due to the temperature rise of the shift unit 40, the flow control valve 75 is opened to increase the amount of CO oxidized air by 20% (step 93). It is determined whether or not the temperature Ts of the shift unit 40 has returned to the high temperature threshold value TH1 or less (step 94). When the temperature Ts becomes equal to or lower than the high temperature threshold value TH1, the amount of reforming water is returned to the rated value (step 95). It returns to the rated value (step 96) and enters a steady operation state. If the temperature Ts of the shift unit 40 does not return below the high temperature threshold TH1, it is determined whether or not the temperature of the shift unit 40 has risen above an upper limit value TH2, for example, 295 ° C. (step 97). Abnormal measures such as stopping the supply of reformed gas from the quality device 20 to the fuel cell 10 and turning on the alarm lamp are performed (step 98).
[0037]
In the above embodiment, after the gas-liquid mixed water vapor passes through the CO purification unit heat exchanger 70, the fuel is mixed with the gas-liquid mixed water vapor, but the fuel is mixed before the CO purification unit heat exchanger 70. You may mix with gas-liquid mixed steam. Further, the fuel may be directly supplied to the reaction chamber 31 of the reforming unit 30 separately from the steam.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing an embodiment of a reformer according to the present invention.
FIG. 2 is a view showing temperature changes in each part of the reformer for reformed gas and steam.
FIG. 3 is a diagram illustrating a response when the temperature of the shift unit becomes lower than a low temperature threshold value.
FIG. 4 is a diagram showing correspondence when the temperature of the shift unit becomes higher than a high temperature threshold value.
FIG. 5 is a diagram showing a corresponding program when the temperature of the shift unit becomes lower than a low temperature threshold value.
FIG. 6 is a diagram showing a corresponding program when the temperature of the shift unit becomes higher than a high temperature threshold value.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Fuel cell, 20 ... Reformer, 30 ... Reforming part, 34 ... Main heat exchanger, 35 ... Evaporator, 36 ... Combustion part, 40 ... Shift part, 60 ... CO purification part, 70 ... CO purification part Heat exchanger, 71 ... mixing section, 72 ... measuring device, 73 ... control device, 74, 75 ... flow control valve.

Claims (5)

  Reformation that reforms fuel and steam into reformed gas by an evaporator that evaporates the reformed water into gas-liquid mixed steam and a reforming section catalyst heated to the active temperature range by the combustion gas generated in the combustion section And heat exchange between the reformed gas generated in the reforming section and the gas-liquid mixed steam, and the reformed gas is cooled to the active temperature range of the shift section catalyst and supplied to the shift section, A main heat exchanger for heating the steam to an activation temperature range of the reforming section catalyst and supplying the steam to the reforming section; a carbon monoxide gas and steam contained in the reformed gas cooled by the main heat exchanger; Is converted into hydrogen gas and carbon dioxide gas by the shift unit catalyst, and carbon monoxide gas contained in the reformed gas derived from the shift unit is reacted with air by the CO purification unit catalyst to form carbon dioxide gas. A CO purification unit that oxidizes, and the evaporator and the main heat exchanger. Reformer, wherein the connected the gas-liquid mixing steam it with a CO purification unit heat exchanger to lower the temperature of the reformed gas flowing through the CO purification unit to the active temperature range of the CO purification unit catalyst. An evaporator that evaporates the reformed water into gas-liquid mixed water vapor, a mixing unit that mixes fuel with the gas-liquid mixed water vapor generated by the evaporator, and a combustion gas generated in the combustion unit are heated to the active temperature range. A reforming unit that reforms fuel and steam into reformed gas using the reforming catalyst, and a reformed gas generated in the reforming unit and a gas-liquid mixed steam in which fuel is mixed in the mixing unit. The reformed gas is cooled to the active temperature range of the shift unit catalyst and supplied to the shift unit, and the mixed steam and fuel are heated to the active temperature range of the reformer unit catalyst to improve the reformed gas. A main heat exchanger to be supplied to the mass part, and a shift unit for converting carbon monoxide gas and water vapor contained in the reformed gas cooled by the main heat exchanger into hydrogen gas and carbon dioxide gas by the shift unit catalyst, , Carbon monoxide gas contained in the reformed gas derived from the shift unit is converted into CO. A CO purification unit to the carbon dioxide gas is reacted with air by unit catalyst, said by the gas-liquid mixing steam before or connected later in the mixing section between the main heat exchanger and the evaporator CO A reforming apparatus comprising a CO purification unit heat exchanger that lowers the temperature of the reformed gas flowing through the purification unit to an activation temperature range of the CO purification unit catalyst. In claim 2, the main the heat exchanger inlet of the gas-liquid mixing steam close the CO purification unit heat exchanger outlet of the gas-liquid mixing steam disposed, the inlet of the gas-liquid mixing steam The reformer is provided with the mixing section between the outlet and the outlet.   In any one of Claims 1 thru | or 3, When the temperature of the shift part measured by this measuring device and the temperature of the shift part measured by this measuring device is lower than a low temperature threshold, the amount of the reforming water is decreased, A controller for increasing the amount of air supplied to the CO purification unit and increasing the amount of reformed water and increasing the amount of air supplied to the CO purification unit when the temperature of the shift unit is higher than a high temperature threshold; A reformer characterized by that.   5. The control device according to claim 4, wherein the control unit reduces the amount of reforming water when the temperature of the shift unit is lower than a low temperature threshold and increases the amount of air supplied to the CO purification unit. Even when the temperature of the shift unit is lower than a lower limit value or when the temperature of the shift unit is higher than a high temperature threshold, the amount of reforming water is increased and the amount of air supplied to the CO purification unit is increased. A reformer characterized in that an abnormal treatment is performed when the temperature of the gas rises above an upper limit value.

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