KR100837679B1 - Fuel processor of fuel cell system - Google Patents

Abstract

A fuel converter for a fuel cell system is provided to allow the reformation reaction to be carried out over the entire region of a reformation part and to reduce the starting time of system operation. A fuel converter(10) for a fuel cell system comprises a burner(11); a reformation part(12) adjacent to the burner; and a CO modification part(13) which reduces the CO of the reformed gas discharged from the reformation part, wherein the reformation part comprises a low temperature reformation layer(12a) where a low temperature active catalyst is installed, and a high temperature reformation layer(12b) where a high temperature active catalyst is installed.

Description

Fuel converter of fuel cell system

1 is an exemplary view of a conventional fuel conversion device;

Figure 2 is another example of a conventional fuel conversion device,

3 is a view of a state partitioned inside the reformer according to the present invention in the fuel conversion device of FIG.

4 is a view of a state in which a baffle plate is formed on the burner side of the reformer according to the present invention;

5 is a view of a state in which a heat transfer coil is installed inside the CO transformer according to the present invention;

6 is a graph of the temperature-time relationship when the heating coil is not installed in the CO transformer (a) and when it is installed (b),

7 is a view of a state in which the heat transfer coil is installed on the outside of the CO transformer according to the present invention,

8 is a view of a state in which a reforming catalyst layer is partitioned and a heat transfer coil is installed inside a CO-modified catalyst layer in the fuel conversion device of FIG. 2;

FIG. 9 is a diagram of a state in which a heat transfer coil is installed outside the CO-modified catalyst layer. FIG.

* Description of the symbols for the main parts of the drawings *

10: fuel converter 11: burner

12: reformer 12a: low temperature reforming layer

12b: high temperature modified layer 12c: diffusion layer

12d: baffle plate 13: CO transformer

13a: hole 13b: diffusion layer

13c: modified catalyst 14: fuel gas / water supply pipe

15: heat exchanger 15a: outer tube

15b: inner tube 16: tube coil

17: reformed gas discharge pipe 18: reformed gas introduction pipe

19: denatured gas discharge pipe 20: combustion gas discharge pipe

21,22: Electric coil

30: fuel converter 31 ~ 39: cylinder

40: heat transfer partition 41: burner

42: preheat layer 43: reforming catalyst layer

43a: low temperature modified layer 43b: high temperature modified layer

44: heat recovery layer 45: CO modified catalyst layer

46,46 ': Air mixture layer 47,47': CO removal catalyst layer

48,48 ': Air inlet 49,50: Heat transfer coil

The present invention relates to a fuel conversion device for converting a hydrocarbon fuel gas into a hydrogen-containing gas that can be used in a stack in a fuel cell system.

As the competition for securing energy resources and environmental pollution is accelerated internationally, a more stable and eco-friendly energy system is required. Accordingly, a fuel cell system with high efficiency and almost no emission of pollutants is drawing attention.

Among them, a domestic fuel cell system includes a fuel processor for converting fuel such as city gas, LPG, kerosene, and the like into a stack, the stack generated by using the converted gas, and the produced fuel. Inverter for converting DC current into AC current, Cogeneration for recovering heat generated from the fuel converter and stack, storing it as hot water, and using it as needed, and fuel gas, air, and water. It is composed of a peripheral device (BOP; Balance of Plant) such as a pump and a valve and a sensor to supply the system to the system.

In general, the fuel converter includes a reformer for generating hydrogen by reacting fuel gas with water vapor, and a CO shift converter and a CO remover for removing carbon monoxide so that the generated gas does not poison the catalyst of the stack. remover).

The reformer produces hydrogen by the following methane-steam reforming reaction.

_{CH 4 + H 2 O → CO} + 3H 2 - 206 kJ / mol ( endothermic)

_{CH 4 + 2H 2 O → CO} 2 + 4H 2 - 165 kJ / mol ( endothermic)

The CO concentration of the reformed gas produced through the reforming reaction is about 10-15%.

Subsequently, the CO transformer denatures CO in the reformed gas to carbon dioxide through the following CO modification reaction to produce hydrogen.

_{CO + H 2 O → CO 2} + H 2 - 41 kJ / mol ( exothermic)

By the reaction, the CO content in the reformed gas is reduced to 1% or less, more preferably about 0.5%.

Subsequently, CO is removed / purified to ppm unit by the selective oxidation reaction as described below.

2CO + O ₂ → 2CO ₂

When the fuel gas purified to the level required for carbon monoxide is supplied to the stack as described above, hydrogen is decomposed into hydrogen ions (H +) and electrons (e-) in the anode of each unit cell constituting the stack. They move to the cathode through the electrolyte membrane and the outer conductor, respectively, and combine with oxygen in the air supplied to the cathode to produce water.

At this time, a current is generated by the flow of electrons, and heat is incidentally generated in the water generation reaction, and the generated current is converted into an alternating current using the inverter as a direct current. In addition, the generated heat is stored as heat storage as hot water using a predetermined heat exchanger, and used for hot water supply and heating as necessary.

1 shows an example of a conventional fuel converter.

In the illustrated fuel converter 10, a burner 11 is installed at a center of an inner lower portion, a reformer 12 is installed in a dome shape surrounding the inner thereof, and a CO transformer 13 is disposed at a predetermined interval thereon. .

In addition, a heat exchanger 15 having a double helix tube structure is installed at an outer circumference of the CO transformer 13, and the outer tube 15a of the heat exchanger 15 includes a fuel gas / water supply pipe 14 and the reformer ( It is connected between the tube coil 16 surrounding the outer periphery of 12, the inner tube (15b) is a reformed gas discharge pipe 17 formed on the top of the reformer 12 and reformed gas introduction pipe (18) of the CO transformer (13). ) Is connected between.

In addition, a modified gas discharge pipe 19 is installed at the CO transformer 13, and a combustion gas discharge pipe 20 is installed at an upper end of the case of the fuel converter 10.

Accordingly, fuel gas and water supplied from the outside flow through the outer tube 15a of the heat exchanger 15 and flow the heat gas and the inner tube 15b transferred from the combustion gas of the burner 11 and the CO transformer 13. It is heated by the reforming gas, preheated and evaporated, and then further heated by the combustion gas while flowing through the tube coil 16 to flow into the lower side of the reformer 12.

Fuel gas and water vapor introduced into the lower side of the reformer 12 are diffused upward and reacted through a reforming catalyst built in the reformer 12 to be reformed into a reformed gas containing a large amount of hydrogen. After rising through the inner pipe 15b of the heat exchanger 15 through the reformed gas discharge pipe 17, the fuel gas and water of the outer pipe 15a are cooled to an appropriate temperature, and then the reformed gas introduction pipe ( It is introduced into the CO transformer 13 through 18).

In the CO transformer 13, a CO denaturation reaction occurs through a CO denaturation catalyst to further reduce CO and increase hydrogen, and the resultant modified gas is supplied to a subsequent line through the modified gas discharge pipe 19. .

The fuel conversion device 30 illustrated in FIG. 2 is another type of conventional fuel conversion device. The fuel conversion device 30 is composed of a plurality of concentric cylinders 31 to 39, and an electrothermal partition 40 is installed at an inner center thereof, and an upper portion thereof is provided. The burner 41 is inserted / installed therefrom, and a series of flow paths are formed between the concentric cylinders 31 to 39 through which fuel gas and steam are introduced and discharged as CO removal gas. The preheating layer 42, the reforming catalyst layer 43, the heat recovery layer 44, the CO modified catalyst layer 45, the air mixture layer 46, and the CO removal catalyst layer 47 are sequentially disposed from the inner side adjacent to the burner 41. It consists of a structure arranged. In addition, the air mixing layer 46 'and the CO removal catalyst layer 47' may be further disposed. In addition, air inlets 48 and 48 'through which air used for selective oxidation is supplied from the outside are formed in a portion immediately before the air mixing layers 46 and 46'.

Therefore, when the combustion gas is discharged through the combustion gas discharge passage formed between the heat transfer partition 40 and the cylinder 39 closest to the heat transfer partition 40, the reforming catalyst layer positioned between the inner cylinder 39 and the outer cylinder 38 thereof. In (43), heat for the reforming reaction is supplied.

In addition, the fuel gas and water vapor supplied from the outside are preheated while flowing along the flow path formed between the CO denaturing catalyst layer 45 and the CO removal catalyst layer 47 and passing through the preheating layer 42.

Subsequently, the reformed gas generated by the reforming reaction in the reforming catalyst layer 43 passes through the heat recovery layer 44, and is appropriately cooled so that the modification catalyst of the CO modification catalyst layer 45 does not cause deterioration. In addition, CO is significantly reduced through CO denaturation and additional hydrogen is generated.

Thereafter, the modified gas is mixed with the air flowing into the air inlet 48 from the air mixing layer 46, and the CO is purified to a ppm unit through selective oxidation in the CO removal catalyst layer 47, and then supplied to the stack. Used for power generation

However, such a fuel converter is used in a small fuel cell system in which necessary devices are built in one case, and a burner which is a calorie supply source of the fuel converter is a fuel supplied from the outside, such as city gas. In addition to the gas, it is also necessary to be able to simultaneously use the gas generated inside the system, i.e. off-gas (hydrogen remaining gas) emitted from the stack, in order to prevent external emissions of flammable and toxic gases.

Therefore, in general, the fuel converter uses a burner that emits flames. When using a flame-emitting burner, the heat of the burner is not uniformly transmitted to the entire reforming part (reformer, reforming catalyst layer), and the flame is not used. Temperature gradients are generated in the reformer depending on the degree of radiant heat transfer therefrom.

Therefore, there is a problem in that the reforming performance of the reforming portion is lowered by lowering the activity of the reforming catalyst in a low temperature region in which heating calories are not sufficiently transmitted.

In order to compensate for this, there is no choice but to increase the amount of the reforming catalyst, which results in an increase in the size of the reforming unit.

In addition, since the calorie supply source is limited to the burner, the calorie of the burner at the time of start-up is intensively transferred only to the local space of the reformer as described above, and the CO-modified part (CO-modifier, CO-modified catalyst layer) located at a predetermined distance therefrom is the waste gas of the burner. That is, it had to be heated only by the amount of heat of the combustion gas discharged.

For example, in the case of FIG. 1, fuel gas and water are preheated by receiving heat from the CO transformer 13, combustion gas, and reformed gas, and then supplied to the reformer 12. However, since the fuel converter is designed to form an optimal heat exchange network at the rated temperature, the CO converter is heated at the start of the reactant, that is, when the temperature of the reformer reaches 600 to 750 ° C. because it is heated only by the amount of combustion gas during operation. The temperature of 13) does not reach the rated operating temperature of 200 ~ 300 ℃ and stays at about 100 ℃.

Therefore, even when fuel gas and water are supplied to the fuel converter in the above state, the CO transformer 13 does not generate heat due to the CO modification reaction and thus maintains a low temperature and the outer tube 15a of the heat exchanger 15. The fuel gas and water flowing into the C) are at room temperature, so that the heat amount of the combustion gas of the CO transformer 13 and the burner 11 is transferred to the reactant water and the fuel gas, whereby the CO transformer 13 is in a rated operation state. The more time is spent to reach, there is a problem that significantly increases the startup time of the system.

In addition, since the fuel gas and water supplied to the fuel converter during the start of operation do not receive sufficient heat from the CO transformer 13, the fuel gas and water are supplied to the reformer 12 at a low temperature, and thus the reactants are supplied at a low temperature. In order to maintain the reformer 12 at a rated temperature of 600 to 750 ° C., there was a problem in that additional heat should be supplied through the burner 11.

That is, there is a problem that the start time of the system is increased because the CO modified part of the fuel converter does not reach the rated operation state quickly, and additional heat must be supplied to the reforming part.

As described above, the overall efficiency of the fuel converter decreases as a result of inefficient use of the heat generated from the burner, which is a heat source. There was this.

Accordingly, the present invention has been made in order to solve the above problems, it is possible to achieve a good catalytic activity over the entire area of the reforming portion is improved reforming performance, there is no need to provide an excessive amount of reforming catalyst to the size of the reforming portion Can be prevented from increasing, and the amount of heat supplied from the burner is more smoothly transferred to the reforming unit, thereby reducing the temperature gradient of the reforming unit, improving the efficiency of the fuel converter, and improving the efficiency of the CO transformer more quickly at the rated operating temperature. It is an object of the present invention to provide a fuel converter of a fuel cell system that can be reached to improve the operational stability of each component of the fuel converter, and further to significantly reduce the startup time of the fuel cell system.

The present invention for achieving the above object,

A fuel converter of a fuel cell system comprising a burner, a reforming unit adjacent to the burner, and a CO modifying unit for reducing CO of reformed gas discharged from the reforming unit.

The reforming unit includes a low temperature reforming layer provided with a low temperature active catalyst and a high temperature reforming layer provided with a high temperature active catalyst.

In addition, the baffle plate protrudes from the burner side of the reforming portion.

In addition, the heat transfer coil is characterized in that the CO-modified part.

That is, the low temperature and high temperature active catalysts enable the reforming reaction to be actively performed in the entire reforming region by using a temperature gradient phenomenon occurring in the reforming portion, and the baffle plate has a heat exchange area between the combustion gas of the burner and the reforming portion and Increasing the time to reduce the temperature gradient generated in the reforming section to more efficiently use the heat of the burner, the heat transfer coil directly heats the CO modified part far away from the burner to quickly reach the rated operating temperature do.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a block diagram of a fuel conversion device improved from the fuel conversion device of FIG. 1 according to the present invention. As described above, the fuel conversion device 10 includes a burner 11 installed at an inner lower center thereof. A dome-type reformer 12 is installed around the 11, and a CO transformer 13 is provided at a predetermined interval on the upper part of the reformer 12, and a heat exchanger 15 is formed on the outer circumference of the CO transformer 13. ) Consists of an installed configuration.

The heat exchanger 15 includes an outer tube 15a connecting a fuel gas / water supply pipe 14 into which fuel gas and water are introduced, and a tube coil 16 surrounding the reformer 12, and the reformer. (12) It has a double helix tube structure composed of an inner tube 15b which connects the reformed gas discharge pipe 17 at the upper end and the reformed gas introduction pipe 18 of the CO transformer 13.

In the above configuration, the present invention is the interior of the reformer 12 is divided into a low temperature reforming layer 12a and a high temperature reforming layer 12b so that the low temperature active catalyst is embedded in the low temperature reforming layer 12a, The high temperature reforming layer 12b is characterized in that a high temperature active catalyst is incorporated.

The high temperature reforming layer 12b in which the high temperature active catalyst is installed is a flame adjacent region extending from the side of the flame of the burner 11 to the entire upper portion of the burner 11 in the reformer 12, and the low temperature reforming layer 12a in which the low temperature active catalyst is installed. ) Is a lower portion of the high temperature reforming layer 12b, and is a region where heat is transmitted relatively less than the high temperature reforming layer 12b.

In addition, an empty space in which the catalyst is not filled is formed in the lower portion of the low temperature reforming layer 12a. The empty space is formed when the fuel gas and the water vapor flow into the lower portion of the reformer 12 from the tube coil 16. Diffusion layer 12c which allows fuel gas and water vapor to be rapidly and uniformly diffused from the discharge port to the entire area of the reformer 12 so that fuel gas and water vapor rise through the entire cross-sectional area of the catalyst layer so that an even reaction occurs in the entire catalyst layer. Function as.

The low temperature active catalyst and the high temperature active catalyst which are installed in the low temperature reforming layer 12a and the high temperature reforming layer 12b are fuel gas and water vapor by means of a mesh-type member called a mesh or a screen. It can be installed so as to be separated from each other and pass each other in a state that can pass.

As described above, the high temperature reforming layer 12b in which the high temperature active catalyst is installed is formed near the flame, which is a high temperature layer through which the radiant heat of the burner 11 is directly transmitted, and is positioned at the lower portion of the high temperature layer to be a relatively low temperature layer. The low temperature reforming layer 12a provided with the low temperature active catalyst is formed in the portion, so that the high temperature active catalyst and the low temperature active catalyst are easily in the respective active temperature ranges even though a high temperature is generated in the reformer 12 and a low temperature gradient occurs in the lower portion. As it can be reached, a smooth reforming reaction is made throughout the reformer 12. That is, the catalytic activity of the reformer 12 as a whole is optimized to improve the reforming performance.

The temperature is measured by installing a temperature sensor at points (a), (b) and (c) of the low temperature reformed layer 12a, the high temperature reformed layer 12b, and the reformed gas discharge pipe 17 of the fuel converter 10. As a result, the temperature of the low temperature reforming layer 12a is 400-500 ° C. and the temperature of the high temperature reforming layer 12b is 600-800 ° C., but a change occurs depending on the position of the burner 11, but the temperature of the reformer 12 is 200-200 ° C. It was confirmed that a temperature gradient of 300 ° C occurred. In addition, the temperature of the reformed gas discharged from the reformer 12 was 600 to 700 ° C.

Therefore, the reforming activity could be maximized by installing the low temperature active catalyst having excellent activity in the 500 ° C region and the high temperature active catalyst having excellent activity at 600 to 750 ° C by dividing the inside of the reformer 12 into two layers.

Meanwhile, as illustrated in FIG. 4, a baffle plate 12d protrudes from a wall surface, that is, an inner wall surface, adjacent to the burner 11 of the reformer 12 at regular intervals. Since this is formed on the inner circumferential surface of the dome-type reformer 12, that is, the cylindrical wall surface, the circular baffle plate 12d is formed at regular intervals in the vertical direction.

In addition, the baffle plate 12d may be formed of one component spirally formed along the inner wall surface.

It is preferable that the temperature gradient of the reformer 12 be minimized as much as possible for the even reforming reaction throughout the reformer 12. The present invention is intended to minimize the temperature gradient by the baffle plate 12d.

The baffle plate 12d suppresses the flow of the combustion gas downward along the inner wall surface of the reformer 12, as shown in the figure. Thus, suppressing the flow of the combustion gas does not affect the smooth discharge performance of the combustion gas, and the length of the combustion gas flow in contact with the reformer 12 is increased by the baffle plate 12d so that the contact area and time are increased. This increase allows heat transfer from the combustion gas to the reformer 12 more efficiently throughout the reformer 12.

That is, the flow rate of the hot combustion gas in the reformer 12 inner wall is reduced, so that the heat transfer amount is improved to the lower side of the reformer 12 and a part far from the flame, thereby reducing the temperature gradient of the reformer upper and lower parts. .

Therefore, more heat is transferred to the reformer 12 so that the catalyst inside can be quickly heated to the activation temperature, and the supply of heat used for the reforming reaction, which is a powerful endothermic reaction, can be made smoothly.

In the embodiment of FIG. 4, the temperature of the same points (a), (b), and (c) is measured as in the embodiment of FIG. 3, and as a result, before the baffle plate 12d is installed, The temperature gradient was 200-300 ° C, but after installation of the baffle plate 12d, the temperature of the low-temperature reformed layer 12a was 480-500 ° C and the temperature of the high-temperature reformed layer 12b was 600-750 ° C, with a maximum temperature of 50 ° C. It was confirmed that the temperature gradient inside the reformer 12 decreased as the temperature was lowered and the temperature deviation was about 100 ° C.

By installing the baffle plate 12d as described above, the temperature deviation inside the reformer 12 cannot be completely eliminated, but by using the high temperature reforming layer 12b, which is a layer on which a high temperature active catalyst having excellent reforming reaction is provided by reducing the temperature gradient. The space can be expanded, and the relatively low temperature reforming layer 12a can be reduced, resulting in a reduction in the size of the reformer 12.

On the other hand, the low temperature active catalyst of the low temperature reforming layer 12a prevents the sulfur components contained in the unvaporized water and the fuel gas from moving to the high temperature reforming layer 12b, and thus the amount of the low temperature active catalyst is relatively higher than that of the low temperature active catalyst. By protecting the high temperature active catalyst of the high temperature reforming layer 12b, the reformer 12 plays a role of maintaining the reforming performance of a predetermined level or more as a whole, and also brings the effect of extending the life of the reformer 12.

Of course, the baffle plate 12d may also be formed on the outer wall of the reformer 12 in the present invention (not shown separately).

On the other hand, as shown in Figure 5, the CO transformer 13 is provided with a heat transfer coil 21 as a heater dedicated to the CO transformer.

To this end, a hole 13a is formed in the center of the container of the CO transformer 13, and the heat transfer coil 21 is helically installed to contact the surface of the hole 13a.

In addition, the reformed gas introduction pipe 18 connected to the upper end of the inner tube 15b of the heat exchanger 15 is formed to extend downward through the hole 13a to be positioned below the CO transformer 13 container. 13b). The modified catalyst 13c provided on the diffusion layer 13b by the hole 13a has a donut shape.

In this case, the heat transfer coil 21 may be installed in contact with not only the inner circumferential surface of the hole 13a but also the outer circumferential surface of the reformed gas introduction pipe 18.

Therefore, when the reformer 12 is first raised to the reaction temperature by the burner 11 at start-up, the heat transfer coil 21 is operated to raise the temperature of the CO transformer 13 to 200 ° C or more. At this time, not only the reaction vessel of the CO transformer 13 but also the reformed gas introduction pipe 18 into which the reformed gas is introduced is simultaneously heated, so that the temperature of the reformed gas introduced into the CO transformer 13 is also increased. By heat transfer from the outside and heat transfer generated while the reformed gas passes through the interior 21, the modified catalyst 13c maintains an overall uniform state without a temperature gradient. The CO modification reaction is actively performed while passing, and heat is generated at this time to stop the operation of the heat transfer coil 21 (stop the power supply).

As described above, the CO transformer 13 is rapidly heated to the rated operating temperature by the operation of the heat transfer coil 21, thereby greatly reducing the startup time of the system.

In addition, since the temperature is maintained by the combustion gas and self-heating, the reformer in the state where the reactants (fuel gas and water) receiving heat from the CO transformer 13 while receiving the heat exchanger 15 are supplied with sufficient heat. Supplied to (12).

As such, the fuel gas and water (steam state) are introduced into the reformer 12 in a state having sufficient calories so that the reforming reaction can be performed without increasing the fuel supply amount of the burner 11 as in the related art. do.

With reference to Figure 6, compare the case (b) and the case (b) is not installed a heat transfer coil 21 in the CO transformer (13).

When the heat transfer coil 21 is not installed (a), when the burner 11 is ignited at the start of the operation of the fuel converter 10 and the reformer 12 temperature is raised to 600 ° C, the temperature of the CO transformer 13 also increases. To reach 100 ° C. At this time, the reactant water and the fuel gas are supplied through the heat exchanger 15 outside the CO transformer 13 to be introduced into the reformer 12, and the reforming reaction proceeds. The temperature of the CO transformer 13 is slowed down when the reactant is supplied. This is a phenomenon in which the heat generated from the CO transformer 13 and the burner 11 is supplied to the reactant. At this time, the reactant obtains a small amount of heat and is supplied to the reformer 12 so that the burner (maintains the temperature of the reformer 12). 11) additional calories are supplied. After the temperature of the CO transformer 13 stays at 100 ° C. for a predetermined time, the temperature of the CO transformer 13 rises again with the heat generated by the CO modification reaction and the heat amount of the burner 11 additionally supplied for the reforming reaction. Equilibrium is reached by reaching the rated 230 ° C. It was confirmed that the time to reach the rated operating temperature of the CO transformer 13 took about 30 to 40 minutes after the addition of the reactants.

On the other hand, when the heat transfer coil 21 is installed (b), when the burner 11 is ignited and the temperature of the reformer 12 reaches 600 ° C., the temperature of the CO transformer 13 is controlled by the heat transfer coil 21. It has already reached the rated 230 ° C. At this time, the reactant is introduced into the heat exchanger 15 outside the CO transformer 13, and the reactant is supplied to the reformer by obtaining a sufficient amount of heat by the temperature of the CO transformer 13 in a rated state, so that additional heat supply through the burner 11 is required. There will be no.

The reformed gas generated in the reformer 12 is introduced into the CO transformer 13, and the modification reaction proceeds in the CO transformer 13 that has already risen to the rated reaction temperature. Since heat is generated by the CO denaturation reaction, the operation of the heat transfer coil 21 is stopped.

As a result of the comparative experiment, when the heating coil 21 is not installed, the operation start time takes 30 to 40 minutes after the input of the reactant due to the time when the temperature of the CO transformer rises to the rated value, but the heating coil 21 In this case, since the temperature of the reformer 12 is raised to 600 ° C., the CO transformer 13 is sufficiently activated and the reaction proceeds smoothly, so that the time required for increasing the rated temperature of the CO transformer 13 is not required. Therefore, the time required for starting the fuel converter operation is reduced by about 30 to 40 minutes.

On the other hand, the CO transformer 13, as shown in Figure 7, the heat transfer coil 22 may be installed in a spiral on the outer peripheral surface of the reaction vessel. At this time, the heat transfer coil 22 is installed to contact the outer tube (15a) of the heat exchanger (15).

In this case, the CO transformer 13 is quickly heated to the rated operating temperature, and the fuel gas and water flowing through the outer tube 15a are more effectively heated, so that the reformer 12 may be rated at the faster operating temperature. The temperature rises and the temperature is maintained, so that there is no need to consume additional calories.

In addition, it is a matter of course that all of the heat transfer coils (21, 22) inside / outside the reaction vessel can be installed and used.

FIG. 8 is an embodiment to which the present invention is applied to the fuel converter of the type shown in FIG. 2. The fuel converter 30 shown in FIG. 2 includes a plurality of concentric cylinders 31 to 39 and an electrothermal partition 40. The combustion gas discharge passage, the reforming catalyst layer 43, the CO removal catalyst layer 47, and the like are sequentially arranged radially outwardly, and the burner 41 disposed at the center thereof is installed downward in the direction of discharge of the flame. As a result, a temperature gradient occurs in a state where the lower side of the reforming catalyst layer 43 has a high temperature and the upper side has a low temperature. (Even in the above-described fuel converter, the low temperature reforming layer 43a, the high temperature reforming layer 43b, and the reforming are generated. As a result of measuring the temperature at each point (a), (b), (c) of the gas discharge part, it has a temperature gradient of 200 to 300 ° C in the same manner as the fuel converter (Fig. 3) of the type described above. Confirmed.)

Therefore, the low temperature reforming layer 43a is formed below the preheating layer 42 and the low temperature reforming layer 43b is formed on the entire lower portion of the low temperature reforming layer 43a. Is formed.

In addition, the inner wall surface of the cylinder 39 forming the combustion gas discharge passage together with the heat transfer partition 40 positioned on the innermost side, the baffle plate 39a protruding obliquely downwardly in a direction opposite to the flow direction of the combustion gas. ) Are formed at regular intervals.

In addition, the heat transfer coil 49 is helically provided on the inner circumferential surface of the cylinder 36 constituting the CO-modified catalyst layer 45.

Accordingly, the fuel gas and water vapor which are sufficiently heated by the heat transfer coil 49 to the CO modified catalyst layer 45 at the rated operating temperature and are sufficiently delivered from the heated CO modified catalyst layer 45 at the start-up. Since the reforming catalyst layer 43 flows through the preheating layer 42, the reforming catalyst layer 43 does not need to further increase the amount of combustion burned by the burner 41 to maintain the rated operating temperature.

In addition, despite the temperature gradient occurring in the reforming catalyst layer 43 as described above, since the low temperature reforming layer 43a and the high temperature reforming layer 43b are disposed accordingly, the reforming reaction may proceed smoothly in the entire region of the reforming catalyst layer 43. In addition, since the heat quantity of the combustion gas is more effectively transferred to the reforming catalyst layer 43 by the plurality of baffle plates 39a formed in the combustion gas passage, the amount of heat supplied by the burner 41 can be used more efficiently. In addition, the reforming catalyst layer 43 can quickly reach the rated operating temperature.

In addition, as illustrated in FIG. 9, the heat transfer coil 50 may be provided on the outer circumferential surface of the outer cylinder 35 of the modified catalyst layer 45.

In this case, various effects as described above are the same, and since the portion in which the heat transfer coil 50 is installed is a moving passage between fuel gas and steam, the fuel gas and steam supplied to the reforming catalyst layer 43 can be preheated more effectively. There is an advantage.

As described above, according to the present invention, by providing a catalyst having a low temperature and a high temperature activity in consideration of the temperature gradient of the reforming unit, good catalytic activity can be achieved over the entire region of the reforming unit, thereby improving the reforming performance, thereby improving the reforming catalyst. There is no need to provide an excess so that the size of the reforming portion can be reduced.

In addition, the heat supplied from the burner is more smoothly transferred to the reformer, thereby reducing the temperature gradient of the reformer, improving the efficiency of the fuel converter, and allowing the CO transformer to reach the rated operating temperature more quickly. The operation stability of each component of the is improved, and furthermore, there is an effect that can significantly reduce the startup time of the fuel cell system.

Claims (7)

A fuel converter of a fuel cell system comprising a burner, a reforming unit adjacent to the burner, and a CO modifying unit for reducing CO of reformed gas discharged from the reforming unit. The reforming unit includes a low temperature reforming layer provided with a low temperature active catalyst and a high temperature reforming layer provided with a high temperature active catalyst. The fuel converter of claim 1, wherein a plurality of circular baffle plates are formed on the burner side of the reforming portion at regular intervals in a vertical direction. The fuel converter of claim 1, wherein a spiral baffle plate is formed on a burner side of the reforming unit. The fuel conversion device of claim 1, wherein a heat transfer coil is installed on an inner circumferential surface of the CO modification part. The fuel conversion system according to claim 4, wherein a reformed gas introducing pipe is disposed at an inner center of the CO modifying unit, and the heat transfer coil is also in contact with an outer circumferential surface of the reformed gas introducing pipe. The fuel conversion device of a fuel cell system according to claim 1, wherein a heat transfer coil is installed on an outer circumferential surface of the CO modification part. The heat exchanger of claim 6, wherein a heat exchanger having a double spiral tube structure is formed around an outer circumference of the CO modifying unit and includes an outer tube through which fuel gas and water flow and a reforming gas flows into the CO transformer. A fuel converter of a fuel cell system, characterized in that the fuel cell system is installed so as to contact the outer tube.

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