JPH01290502A - Fluidized bed type reforming furnace - Google Patents

Abstract

PURPOSE:To improve the uniform heat transfer of catalyst pipes and the response velocity for the variation of load to be efficiently allowed to reform in the fluidized bed type reforming furnace in which hydrocarbon fuel is changed into the gas the main component of which is hydrogen by disposing catalyst pipes in the specified arrangement. CONSTITUTION:Air and hydrocarbon fuel, such as city gas, preheated by a preheater 19 are supplied to a gas burner 16, and the gas fuel is burnt in a combustion chamber and the burnt gas is introduced from nozzles 40 to a fluidizing chamber 17. By this introduction of gas, the fluidizing and medium filled in the fluidizing chamber 17 is fluidized and heated to form a fluidized bed F, which uniformly heats the catalyst pipes 18. Plural pipes 18 are provided respectively in vertical direction and horizontal direction keeping horizontal state in the fluidizing chamber 17, and consequently, the number of the catalyst pipes 18 which are buried in the fluidized bed is increased or decreased according to the height caused by the variation of the load of the reforming furnace, and the fluctuation width of temp. of the fluidized bed F is reduced. Moreover, spiral body 70 is provided in the catalyst pipe 18 so that city gas and steam are flowed in a spiral flow in the catalyst layer 60 densely filled with catalyst, and reforming is efficiently carried out.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a fluidized fluid that can extract gas containing hydrogen as a main component from a hydrocarbon fuel such as city gas and water vapor and supply it to, for example, a fuel cell. Regarding the bed type reforming furnace, in detail, the differential pressure in the fluidized bed section is small, so there is little power loss.
In addition, there is little change in fluidized bed temperature even with load fluctuations.
The present invention also relates to a fluidized bed reforming apparatus that can uniformly heat the raw material in the catalyst tube and reform it extremely efficiently.

[Prior Art] Conventionally, this type of fluidized bed reformer has a plurality of catalyst tubes arranged vertically inside the reformer, a fluidized bed is formed between the catalyst tubes, and a fluidized bed is formed between the catalyst tubes. The fluidized medium heated by the combustion of fuel and air supplied from the bottom of the bed is brought into contact with the catalyst tube to heat the catalyst tube, and the hydrocarbon fuel supplied inside the catalyst tube is reformed by adding steam. It is configured as follows.

[Problem B to be solved by the invention] In such a conventional reforming furnace with catalyst tubes installed in the vertical direction, it is necessary to bring the fluidized medium into contact with the catalyst tubes that are long in the vertical direction. Because the height (the height when the fluidized medium is not flowing) is increased, for example, by about a hand of the length of the catalyst tube, the differential pressure of the gas in the fluidized bed section increases, resulting in a large power loss. There is a problem with that. Furthermore, the higher the height of the stationary bed, the higher the flying height of the fluidized medium becomes, so the free board needs to be made higher, which increases the height of the furnace body. In addition, in order to keep the freeboard height low, a device is required to collect the wave medium that flies out of the furnace.

On the other hand, conventional fluidized bed reforming furnaces with catalyst tubes oriented vertically have the advantage of being able to maintain a uniform temperature inside the bed, which is a characteristic of a fluidized bed, and the temperature distribution of the catalyst tubes is controlled. Although it has the advantage of being small, providing uniform heat transfer, and having a fast response speed to changes in load, on the other hand, the height of the fluidized bed is linear with the load (gas amount). For example, as the load (gas amount) increases, the height of the fluidized bed gradually curves upward and increases. Even if the ratio is halved, the proportion of the fluidized medium in contact with the vertically oriented catalyst tubes does not decrease to half, so the amount of heat exchanged increases and the fluidized bed temperature decreases, reducing the rate of contact between the fluidized medium and the vertically oriented catalyst tubes. Another problem is that it cannot be modified.

The present invention was developed in view of the above-mentioned problems.The height of the fluidized bed can be reduced, pressure loss and power loss are small, the height of the furnace body does not become unnecessarily high, and it is also effective against load fluctuations in the reforming furnace. It is an object of the present invention to provide a fluidized bed type reforming furnace which can reduce changes in fluidized bed temperature even when the fuel is heated, and can carry out predetermined reforming according to the load.

[Means for Solving the Problems] In order to achieve the above object, a fluidized bed reformer according to the present invention has a catalyst tube filled with a catalyst inside a fluidized chamber, and a hydrocarbon-based reformer is provided in the catalyst tube. In a fluidized bed reformer that converts hydrocarbon fuel into a gas containing hydrogen as a main component by passing fuel and steam through the catalyst tube and heating the catalyst tube from the outside using a fluidized bed, the catalyst tube is used for gas dispersion. The configuration was such that multiple tubes were placed horizontally in the flow chamber above the plate, both vertically and horizontally.

Further, the horizontal catalyst tube has a spiral band extending along the inner circumferential wall of the tube and in the longitudinal direction of the tube, and is a catalyst tube in which the catalyst is packed in the tube in a close-packed state. did.

Further, the gas distribution plate is composed of two partition plates arranged with a gap in the vertical direction, and a large number of gas nozzles provided vertically passing through the partition plates, and the gap is used as a gas fuel supply passage. In addition, the gas distribution plate is formed with a small hole for introducing gas fuel into the wall of the gas nozzle located in the gas fuel supply passage.

[Function] By arranging a plurality of catalyst tubes horizontally in the vertical and horizontal directions, the set height of the catalyst tubes in the flow chamber or the installation interval between the catalyst tubes in the height direction can be adjusted according to the flow medium. Correlated with the filling amount, the number of water submerged in this fluidized bed changes when the fluidized bed height is changed in response to changes in the reformer load, i.e. the fluidized medium contacts the catalyst tubes. It is now possible to adjust and set the ratio so that it changes, and the total amount of heat transferred from the fluidized bed to the catalyst tubes increases or decreases in response to increases or decreases in the load (gas amount) of the reformer.
Fluidized bed temperature fluctuation range can be reduced.

As a result, even when the reformer load decreases, multiple-end heat exchange is performed as in the case of conventional catalyst tubes installed vertically, and the fluidized bed temperature decreases (71).
i is avoided, and the reforming furnace is operated stably even under low load.

Since the catalyst tube is installed horizontally, the height of the stationary bed of the fluidized medium can be extremely low in relation to the above-mentioned set height position, and it is possible to create a so-called shallow bed. The pressure loss of the working gas is reduced, and this power loss is also reduced.

For this reason, the height of the fluidized medium that protrudes is also reduced, the free board can also be kept low, and the size of the reforming furnace does not increase.

Under such conditions, the fluidized bed reforming furnace of the present invention exhibits the original characteristics of fluidized bed heat transfer, while sufficiently maintaining uniform heat transfer to the catalyst tubes and good response speed to load changes. It is capable of reforming hydrocarbon fuels with high efficiency.

In addition, if a spiral band is provided on the inner wall of the catalyst tube and the catalyst is packed in the catalyst tube in a close-packed manner, even if the catalyst tube is horizontal, the catalyst will move downward under its own weight. This prevents as much as possible from clogging and sparsing the upper part, and even if a space is formed above, the action of the spiral band gives a swirling flow to the gas flow in the pipe, so that only the upper gap is filled with gas. This prevents the catalyst tube from becoming partially abnormally high in temperature due to the flow of the catalyst tube stopping downward, and the packed bed heat transfer coefficient is further improved by this band.

Furthermore, by introducing gas fuel into the numerous gas nozzles of the gas distribution plate and supplying it together with fluidizing air into the fluidized bed, the gas fuel is evenly distributed throughout the fluidized bed and burned, and the temperature of the fluidized bed is lowered. A plurality of catalyst tubes extending horizontally are evenly heated.

[Example] Examples will be described below with reference to the drawings.

Fig. 1 is a longitudinal sectional view of a fluidized bed reforming furnace according to an embodiment of the present invention, Fig. 2 is a sectional view taken along the line ■ to ■ of Fig. %1, and Fig. 3 is a section of FIG. 4 is an enlarged longitudinal cross-sectional view, and FIG. 4 is a view taken along the line ■ to ■ in FIG. 3, showing how to attach the spiral band. FIG. 5 is an enlarged detailed view of the gas distribution plate.

Reference numeral 10 denotes a reforming furnace body, and a gas distribution plate 12 is installed at the bottom of the reforming furnace body so as to cross the inside of the furnace, and a combustion chamber 14 is defined. A gas burner 16 is installed on the furnace wall of the combustion chamber 14, and a gas fuel pipe and an air supply pipe (not shown) are connected to the burner 16.

A fluidization chamber 17 is formed above the gas distribution plate 12, and a large number of catalyst tubes 18 are arranged horizontally in the fluidization chamber 17 in the vertical and horizontal directions. They are installed in tiers and in a staggered arrangement in the vertical direction. Reference numeral F indicates a fluidized bed formed by a fluidized medium with a small particle size such as sand, and reference numeral 17a indicates a free board (empty column) above the fluidized bed F. The upper part of the free board 17a is connected to the gas burner 16. A preheater 19 for preheating supplied gas fuel or combustion air, gas fuel introduced into the gas nozzle of the distribution plate 12 (described later), or hydrocarbon fuel such as city gas supplied into the catalyst pipe 18 using combustion exhaust gas. is provided, and an exhaust gas outlet 3 is provided downstream of the gas flow of this preheater 19.
0 is set.

As details of the gas distribution plate 12 are shown in FIG. 5, an upper partition plate 12a and a lower partition plate 12 are arranged at intervals in the vertical direction.
b are Rn across the furnace body 10, the gap constitutes a gas fuel supply passage 41, and the upper and lower partition plates 12a,
A gas nozzle 40 is fixedly formed by vertically penetrating through 12b, and the gas fuel supply passage 4 of this gas nozzle 40
A gas fuel introduction hole 40a is provided in the wall surface of the portion located at 1. The lower end of this gas nozzle 40 is opened to the combustion chamber 14, and the upper part thereof has an outlet hole through which the combustion gas combusted in the combustion chamber 14 and the gas fuel that has flowed in from the gas fuel introduction hole 40a are jetted into the fluidization chamber 17. 40b, and a lid 40c is attached to its upper end to prevent the fluid medium from entering the blow-off hole 40b. Further, a gas fuel supply port 41a is provided in the wall of the furnace body 10 communicating with the gas fuel supply passage 41. A heat insulating material 13 is applied to the upper and lower partition plates 12a and 12b, respectively. Note that this upper and lower partition plate 12a.

12b and its heat insulating material 13 may be made of wood pipe to form a water-cooled panel.

As shown in FIG. 2, one end of the catalyst tube 18 is fixed to the furnace wall of the furnace body 10, the other end is free, and the free end is bent to form a U-shape. A pair of continuous catalyst tubes 18 (upper and lower) are arranged horizontally at equal intervals and alternately at different heights so as to form four stages in the vertical direction. Note that the reference numeral 10a is a heat insulating material provided on the inner surface of the furnace wall. And this catalyst tube 18
A flange 18a is fixed to the end surface protruding outward from the furnace wall, and the flange 18a has a heat insulating material 18d inside to be inserted into the end of the catalyst tube 18 to press down the catalyst and keep it in a close-packed state. The companion flange 18b attached with the presser cylinder 18c protruding is attached with a gasket interposed between both flanges 18a and 18b using a port nut (not shown) (see Fig. 3). By removing the flange 18b, the catalyst 60 or the spiral band 70 can be replaced. As shown in FIG. 2, an upper large-diameter tube 51 and a lower large-diameter tube 52 are supported by the boiler furnace body 10 at obliquely upper and lower positions of the portion of the catalyst tube 18 that protrudes from the furnace body 10, respectively. The protruding portions of the upper and lower catalyst tubes 18 from the furnace body lO are connected by small diameter tubes 51a and 52a between the upper large diameter tube 51 and the lower large diameter tube 52, respectively, so that thermal expansion can escape. ing. Hydrocarbon fuel such as city gas heated to about 550° C. and steam are introduced into the catalyst tube 18 from the lower large diameter tube 52 through the small diameter tube 52a, and steam is introduced into the catalyst tube 18.
8, hydrogen gas and carbon monoxide gas generated by external heating from the fluidized bed to a temperature of about 700°C are introduced into the upper large diameter pipe 51 through the small diameter pipe 51a of the upper catalyst pipe 18. Ru.

Inside the catalyst tube 18, as shown in detail in FIGS. 3 and 4, a relatively thin spiral band 70 made of stainless steel or the like is provided on the inner wall surface of the tube over the entire length of the tube 18. The portion of the catalyst tube 18 located in the wave chamber 17 is filled with a large number of vanadium or nickel catalysts 60 having solid dimensions of about 20φ x 20H in a close-packed state.
Furthermore, the portion protruding from the flow chamber 17 to the outside of the furnace is filled with a filling material 8 made of stainless steel or the like, which maintains the porosity even when a large number of pieces are pressed together and is filled with gas, so that the gas passage resistance can be reduced.
A catalyst 60 filled with 0 and filled in the catalyst tube 18
The presser cylinder 18c of the companion flange 18b is pressed through the filler 80 so as to maintain a close-packed state. Note that the catalyst 6 is connected to the catalyst tube 18.
When filling 0, it is also possible to fill it together with the spiral band 70 so as to be in a close-packed state.

In the fluidized bed reforming furnace configured as described above, gas fuel such as city gas preheated in the preheater 19 and air are supplied to the gas burner 16, the gas fuel is combusted in the combustion chamber 14, and the gas nozzle 40 The combustion gas is introduced into the flow chamber 17, and a part of the gas fuel is also introduced into the gas fuel supply passage 41 of the gas distribution plate 12 through the fuel supply port 41a and introduced into the interior through the introduction hole 40a of the gas nozzle 40. The fluid is supplied into the flow chamber 17. By introducing this combustion gas into the fluidized chamber 17, the fluidized medium filled in the fluidized chamber 17 is fluidized and heated to form a fluidized bed F. At the same time, the gaseous fuel is combusted throughout the fluidized bed F, and the entire fluidized bed F is heated more evenly. In this way, the catalyst tubes 18 are heated evenly.

Therefore, in the embodiment of the present invention, the catalyst tubes 18 are installed so that when the height of the fluidized bed F is changed in response to changes in the reformer load, the number of tubes buried in the fluidized bed F changes. For example, when the reformer load reaches the maximum, the gas fuel and gas nozzles to the gas burner 16 are set. 40 is maximized, the height of the fluidized bed F increases to the level of A in FIG. 1, and all catalyst tubes 18 are submerged in the fluidized bed F.

In addition, in an intermediate load state, the gas fuel supply amount and air supply amount are reduced accordingly, and the fluidized bed F
The height of is reduced to the level of B or C in Figure 1,
Among the catalyst tubes 18, those in the uppermost stage or in the upper two rows are exposed from the fluidized bed F. Further, when the lowest load condition is reached, the gaseous fuel supply amount and air supply amount are reduced to the minimum amount, and the height of the fluidized bed F is reduced to the level D in FIG. 1. This allows the heat exchanger tubes 1 in the top and middle 2nd tier to
8 are exposed from the fluidized bed F, and only the lowest catalyst tube 18 is buried in the fluidized bed F.

In this way, when the height of the fluidized bed changes in response to changes in the load of the reforming furnace, the number of catalyst tubes 18 buried in the fluidized bed increases or decreases, and the heat transfer area increases or decreases. Therefore, the total heat transferred from the fluidized bed F to the catalyst tubes 18 increases or decreases in accordance with the increase or decrease in load, and the range of fluctuation in the temperature of the fluidized bed F becomes significantly small. Therefore, even when the load on the reformer decreases, unlike in the past, a large amount of heat is exchanged and the fluidized bed temperature suddenly drops. It is possible to do so. In addition, it is possible to follow changes in load down to low loads, and at the same time, it is possible to change quickly. The temperature of fluidized bed F is 8
The temperature is maintained constant in the range of 00 to 900°C.

On the other hand, heated city gas, natural gas, or hydrocarbon fuel such as naphtha (described as city gas in this embodiment) and steam are passed from the lower large-diameter pipe 52 through the small-diameter pipe 52a to the lower catalyst pipe. 18, first smoothly passes through 80 layers of packing material, passes through a layer of catalyst 60, turns around at the bend of the U-shaped tube, and passes through the upper catalyst tube 18. During this time, the entire structure is The evenly heated fluidized bed F and the external catalyst absorb heat evenly from the fluidized bed F and gradually decompose it, reforming it into a gas with a high concentration of hydrogen and carbon monoxide. Hydrogen gas is discharged from the upper large-diameter pipe 51 via 51a, and a large amount of hydrogen gas is sent to the fuel cell. In this reforming process, a spiral band 70 is formed inside the catalyst tube 18.
Gas such as city gas, steam, or reformed gas as a raw material flows in a swirling flow through the 60 layers of catalyst packed in the most densely packed state, so it flows evenly through the 60 layers of the catalyst, resulting in extremely efficient reformation. As quality action takes place,
Even if a gap is formed in the upper part of the catalyst tube 18, the swirling flow of gas strongly prevents the phenomenon that the gas flows only through the upper gap and does not flow to the catalyst 60 layer below. In addition, the catalyst tube 18 itself is prevented from being damaged due to abnormally high temperature in some parts, and deterioration of the catalyst 60 itself due to local heating is avoided as much as possible, so that stable operation of the reforming furnace can be performed. Ru. Catalyst tube 1
8 has a U-shape, so it is extremely flexible against elongation due to heat, and even if the catalyst tube 18 is fixed to the furnace wall at one end, it can be deformed and damage can be prevented. Ru.

In this way, by installing the catalyst tube 18 in a horizontal state, the static height of the fluidized bed F can be made extremely low, so the pressure loss due to fluidization is reduced, and therefore the power loss is also reduced. The height of the free board 17a is small, and the height of the fluid medium is also small, so that the free board 17a may have a low height.

Note that the combustion gas that has passed through the fluidized bed F is transferred to the freeboard 17a.
The gaseous fuel and combustion air are introduced into the preheater 19 provided at the upper part thereof, where WJ8 is applied to the gaseous fuel and combustion air to exchange heat and preheat, and then the gas is discharged out of the furnace from the outlet 3o.

Note that the catalyst tube 18 is not limited to the case where the free end side is bent to form a single U-shape as shown in FIG. Sometimes.

Further, in this embodiment, the catalyst tubes 18 are arranged in four stages in the vertical direction, but in the present invention, they may be arranged in three stages, two stages, or more.

Moreover, if the spiral band 70 is coated with ceramic paint to reduce the radiation heat transfer effect of far infrared rays, the packed bed heat transfer coefficient can be further improved by providing a swirling flow. This allows the outer surface area of the catalyst tube 18 to be further reduced.

[Effects of the Invention] Since the present invention is configured as detailed above, it achieves the following excellent effects.

In the reforming furnace according to claim 1, the height of the fluidized bed can be lowered, pressure loss and power loss can be reduced, the height of the furnace body can also be lowered, and the fi Changes in the moving bed temperature can be reduced, stable operation is possible even in low load conditions, and changes in load can be followed up to low loads and can be changed quickly.

In the reforming furnace according to claim 2, the catalyst is prevented from shifting downward in the horizontal catalyst tube as much as possible, and the scum waves in the tube as a swirling flow, so that it flows evenly in the catalyst layer. The reforming action is carried out extremely efficiently, and since the gas flows evenly through the catalyst tube, the catalyst tube is prevented from being locally heated and damaged, and the catalyst itself is prevented from deteriorating due to local heating. Enables stable and efficient operation.

In the reforming furnace according to claim 3, the entire fluidized bed is heated to a more even temperature by spreading and burning the gas fuel throughout the fluidized bed, and the catalyst tubes are heated evenly, so that extremely stable reforming can be achieved. It becomes possible to perform quality actions.

[Brief explanation of the drawing]

The drawings are all related to embodiments of the present invention, and the first
The figure is a schematic vertical cross-sectional view of a fluidized bed reforming furnace, Figure 2 is a cross-sectional view taken along the line II-II in Figure 1, Figure 3 is an enlarged vertical cross-sectional view of section X in Figure 2, and Figure 4 is a cross-sectional view taken along the line ■ to ■ of Figure t53,
FIG. 5 is an enlarged view of the gas distribution plate. lO...Reforming furnace furnace body, 12...Gas distribution plate, 1
2a, 12b--Partition plate, 40--Gas nozzle, 40a--Gas fuel introduction hole, 41--Gas fuel supply passage, 14--Combustion chamber,
16... Gas eighth, 17... Flow chamber, 1
8...Catalyst tube, 60...Catalyst, 70...
-Spiral band. Patent applicant: Ube Industries, Ltd. Figure 2 Figure 3

Claims (3)

[Claims] (1) The fluidization chamber has a catalyst tube filled with a catalyst, and by passing hydrocarbon fuel and steam through the catalyst tube and heating the catalyst tube from the outside using a fluidized bed, the hydrocarbon fuel is mainly converted to hydrogen. In a fluidized bed reforming furnace configured to convert gases into component gases, a plurality of the catalyst tubes are arranged horizontally in the fluidization chamber above the gas distribution plate in the vertical direction and in the horizontal direction. A fluidized bed reforming furnace. (2) The horizontal catalyst tube has a spiral band extending along the inner peripheral wall of the tube and in the longitudinal direction of the tube, and the catalyst tube is filled with catalyst in a close-packed state. The fluidized bed reforming furnace according to claim 1, characterized in that: (3) The gas distribution plate consists of two partition plates arranged with a gap in the vertical direction, and a large number of gas nozzles provided vertically penetrating the partition plates, and supplies gas fuel to the gap. The fluidized bed type according to claim 1 or 2, characterized in that the gas distribution plate is formed as a passage and has small holes for introducing gas fuel in the wall of the gas nozzle located in the gas fuel supply passage. Reforming furnace.