JP2730283B2 - Reforming tube and reformer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method of mixing a hydrocarbon-based fuel, such as city gas, LPG, methanol, and kerosene, with steam as a raw fuel in a tube, flowing the mixture, and heating the mixture from the outside. The present invention relates to a reforming tube that obtains a gas mainly composed of hydrogen and carbon monoxide, and a reforming device equipped with the reforming tube.Specifically, the pressure loss in the reforming tube is reduced to reduce the required heat transfer area and the amount of catalyst. The present invention relates to a reforming pipe and a reforming apparatus.

[Conventional technology]

A reforming pipe and a reforming device for reforming a hydrocarbon fuel such as city gas are disclosed in, for example, Japanese Patent Application Laid-Open No. 1-290502.
The reforming tube is filled with a reforming catalyst over the entire length of the tube, and the reforming catalyst is densely packed in the tube by pressing a packing packed at the end of the tube with a holding cylinder. ing. A hydrocarbon-based fuel such as city gas and steam are supplied into the inside of the reforming tube, so that the catalyst layer is circulated. Then, the reforming tube is heated by being brought into contact with the heated fluidized bed from the outside, whereby the hydrocarbon-based fuel absorbs heat while passing through the catalyst layer, and is gradually decomposed by the action of the catalyst, and is decomposed with hydrogen. It is reformed into a gas with a high concentration of carbon oxide.

[Problems to be solved by the invention]

However, in the reforming tube in which the catalyst is densely filled as described above, the pressure of the raw fuel such as city gas is 1 kg / cm, for example.
^When it is as low as about ² G, the amount of raw fuel gas that can flow through one reforming pipe is limited due to the pressure loss in the reforming pipe, and can be increased only to a certain extent. Therefore, the heat transfer of the packed bed of the catalyst in the reforming tube is rate-limiting, and a large heat transfer area is required. That is, if the amount of the raw fuel gas flowing in the tube is small, the heat transfer coefficient inside the tube is small, and this becomes a bottleneck, so that the heat transfer area must be increased in order to provide a predetermined amount of heat required for reforming. That is, it is necessary to increase the pipe diameter or the pipe length. As the tube diameter or the tube length increases, the amount of the catalyst packed in the tube also increases.
Double filling was also uneconomical.

The present invention has been made in view of such a problem, and reduces the pressure loss in the reforming pipe so that the amount of the raw fuel gas flowing through the pipe is large even when the supply pressure of the raw fuel gas is relatively low. It is an object of the present invention to provide a reforming pipe and a reforming apparatus capable of reducing a heat transfer area and a catalyst amount necessary for obtaining a predetermined reforming rate.

[Means for solving the problem]

In order to achieve the above object, the present invention provides: (1) a reforming pipe for reforming a hydrocarbon-based fuel by heating from the outside, comprising a reforming catalyst and a space having a required space ratio inside. A catalyst-packed layer formed by uniformly mixing a metal filler with a good thermal conductivity at a predetermined volume ratio and pressing it in with a pressing member to fill in a dense state. , A reforming tube in which a predetermined space ratio is provided inside to reduce gas flow resistance. (2) The reforming tube according to the above (1), wherein the reforming tube is a horizontal reforming tube. (3) The hydrocarbon-based fuel reforming catalyst is uniformly mixed with a metal filler having a space portion having a required space ratio and having good heat conductivity at a predetermined volume ratio. The horizontal reforming tube, which has a catalyst packed layer formed by being pressed into a dense state by a pressing member and having a predetermined space ratio therein to reduce gas flow resistance, is formed by a fluidized bed. This is a reforming apparatus for heating.

[Action]

In the reforming tube according to claim (1), the reforming catalyst and the packing material (for example, an annular shape or the like made of a material having good thermal conductivity (for example, metal) and having a space therein) are provided at a predetermined volume ratio. Then, for example, the catalyst and the filler are uniformly mixed such that the volume ratio is 2: 1 to form a catalyst packed layer, which is densely provided in the reforming tube. Accordingly, a predetermined void ratio is secured in the reforming tube, the gas flow resistance (pressure loss) is reduced, a larger amount of gas flows, the packed bed heat transfer coefficient in the tube is increased, and the heat transfer area is reduced. . Therefore, the number of passes and the amount of catalyst in the reforming tube are reduced.

In the reforming tube of claim (2), in addition to the above-mentioned operation, furthermore, since the reforming tube is horizontal, powdering of the catalyst is prevented, and the life of the catalyst is significantly extended. In other words, the reforming tube has a larger thermal expansion coefficient than the catalyst, and the reforming tube expands during operation. Does not occur. In the meantime, in the vertical reforming tube which is generally long and used in the vertical direction, the reforming tube swells during operation and a gap is formed in the catalyst layer, and the formed gap is clogged with the catalyst by its own weight. Then, at the time of the stop, the reforming tube shrinks to crush the catalyst and powder it. For this reason, the life of the catalyst was extremely short. In the horizontal reforming pipe of the present invention, particularly when the reforming apparatus is used as a fuel cell reforming apparatus, the apparatus is frequently started and stopped, which is extremely advantageous in the life of the catalyst.

In the reforming device of claim (3), in addition to the effects of (1) and (2), since the heating of the horizontal reforming tube is performed by the fluidized bed, an efficient reforming operation is performed, and the reforming is performed. The tubes are heated evenly, avoiding local heating and extending the life of the reforming tubes and catalyst. By making the reforming tube horizontal, the height of the fluidized bed can be reduced as compared with the vertical reforming tube, and the overall height of the apparatus can be reduced, and the power of the air blower can be reduced. .

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

1 and 2 show the overall configuration of a fluidized bed reforming furnace as a reforming apparatus equipped with a reforming tube of the present invention. FIG. 1 is a vertical front view, and FIG. 2 is FIG. FIG. 3 is a perspective view showing various examples of the packing used in the present invention, and FIG. 4 is a diagram in which the reforming catalyst and the packing are mixed in a horizontal catalyst tube of the present invention. It is a longitudinal cross-sectional view which shows the state in which the catalyst packed layer was formed.

First, the overall configuration of the fluidized bed reforming furnace will be described with reference to FIGS.

Reference numeral 10 denotes a furnace body, in which a gas dispersion unit 20 is installed on the furnace bottom 10a of the furnace body 10 in the flow chamber 70, and at a predetermined distance from the gas dispersion unit 20 in the flow chamber 70 above it. A plurality of catalyst tubes 80 as upper and lower (four upper and lower stages in this embodiment) reforming tubes are flow chambers.
It is positioned horizontally across 70. As shown in FIG. 1, the catalyst tubes 80 of the lowermost stage, the second stage, the third stage, and the fourth stage are connected at their ends to each other by a communication tube 80a.
The end of the stepped catalyst tube 80 opposite to the above is communicated with a communication tube 80b. Reference numeral 81 denotes a lower supply pipe (header) for supplying a hydrocarbon-based fuel such as city gas and steam into the catalyst tube 80, and reference numeral 82 denotes hydrogen gas or carbon monoxide gas obtained by reforming the catalyst tube 80. Is an upper discharge pipe (header) from which is taken out. The gas dispersion unit 20 is branched from the air header 31 and
The air pipe 30 placed and arranged on 10a and this air pipe 30
A large number of air distribution pipes 40 attached at intervals in the axial direction of the gas fuel supply pipe, and a gas fuel branched from the gas fuel supply header 51 at a position above the air distribution pipe 40 and arranged substantially in parallel with the air pipe 30. The pipe 50 is composed of a number of gas fuel distribution pipes 60 attached to the gas fuel pipes 50 at an interval in the axial direction thereof and located between the adjacent air distribution pipes 40.
When not operating, the fluidized catalyst 100 is filled (stationary) with the upper surface positioned at a predetermined height above the furnace bottom 10a. 1 and 2 show a state in which the fluidized medium 100 is fluidized to form a fluidized bed F. A flue gas take-out pipe 90 is attached to the free board 70a above the flow chamber 70. 90a is an exhaust gas discharge pipe.

As shown in FIG. 4, the catalyst tube 80 is densely filled with a catalyst packed bed 130 formed by uniformly mixing the reforming catalyst 110 and the packing material 120 over the length of the catalyst tube 80. . The catalyst filling layer 130 in each catalyst tube 80 is densely filled by pushing the end of the catalyst tube 80 on the header 81, 82 side by the holding tube 83. The reforming catalyst 110 shown in FIG. 4 has a cylindrical shape as an example. As the reforming catalyst 110, a vanadium or nickel-based catalyst is used. The filler 120 is made of stainless steel, and is shown as a cylindrical Raschig ring shown in FIG. 3 (a).

FIG. 3 shows examples of various packings applied to the present invention. 3A is a Raschig ring 120, FIG. 3B is a lessing ring 121, and FIG. 3C is a Berl saddle 12.
2, FIG. 3 (d) is an interlock saddle 123, FIG. 3 (e) is a terraret 124, FIG. 3 (f) is a pole ring 1
25, each of which has a space inside
It has 120a-125a and has the required space ratio.

The reforming catalyst 110 and the fillers 120 to 125 are uniformly mixed at a volume ratio of, for example, 2: 1 to form a catalyst packed layer 130 in the catalyst tube 80. Thereby, the catalyst packed bed 130
Is provided with a predetermined porosity, and the amount of raw fuel gas that can flow per catalyst tube 80 even if the pressure difference (pressure loss) of the catalyst tube 80 is kept the same as that of a conventional catalyst tube filled only with catalyst. Is increased, for example, to about 30%. Therefore, the packed bed heat transfer coefficient (packed bed heat transfer amount) in the catalyst tube 80 is increased, and as a result, the heat transfer area is also reduced.
% Reduced and balanced. As a result, the amount of catalyst is about
50%.

In the present invention, on the premise that a minimum amount of catalyst necessary for obtaining a predetermined reforming rate (for example, 93% or more) is secured, the catalyst amount is set to be 2/3 or more of the volume of the catalyst tube 80. The catalyst 110 and the fillers 120 to 125 are uniformly mixed to form the catalyst packed layer 130.

Such a catalyst tube 80 is evenly heated by the catalyst with the fluidized bed F as shown in FIGS. That is, the fluidized bed F is fluidized by the air for combustion and fluidization supplied from the many air dispersion pipes 40 of the gas dispersion section 20 and has a higher bed height, and is supplied from the gas fuel dispersion pipe 60. A predetermined temperature, for example, a uniform temperature of about 800 ° C. is maintained by the combustion of the gaseous fuel, and the catalyst tube 80 is uniformly heated by being brought into contact with or buried in the fluidized bed F. Then, hydrocarbon fuel such as city gas and steam supplied from the lower supply pipe 81 into the lowermost catalyst pipe 80 and the communication pipes 80a and 80b are transferred from the lowermost catalyst pipe 80 to the upper catalyst pipe 80.
Through which the hydrocarbon fuel and steam,
The hydrocarbon-based fuel is reformed into a gas having a high concentration of hydrogen gas or carbon monoxide gas by the action of the reforming catalyst 110 while the reforming catalyst 110 absorbs heat uniformly through the filler 120. The gas thus obtained is taken out from the upper exhaust pipe 82 of the uppermost catalyst pipe 80, and the hydrogen gas is used for a fuel cell or the like. The flue gas rises on the free board 70a, is sucked into the flue gas discharge pipe 90, and is taken out from the flue gas discharge pipe 90a.

The catalyst tube 80 is arranged in a horizontal state, and the thickness of the catalyst layer in the vertical direction is small. For this reason, even when the fluidized bed reforming furnace is used as a fuel cell reformer in which operation and shutdown are performed relatively frequently, the catalyst packed bed 130 is compressed when the catalyst tube 80 expands and contracts due to heat. Therefore, the catalyst 110 itself is not crushed or crushed.

Here, an experimental example using a conventional catalyst tube and the catalyst tube 80 according to the present invention will be described.

As the catalyst tube 80, an inner diameter of 80 mm and a filling length of the catalyst packed layer 130 of 1600 mm (per one) are connected in a series (series) in the height direction of four rows [same as shown in FIGS. In the direction, 30 tubes (4 tubes in FIGS. 1 and 2) are arranged in each row in the height direction, and a catalyst tube to which city gas as a raw fuel gas is supplied in parallel is used.

The reforming catalyst 110 is a nickel-based catalyst with an outer diameter of 16 m.
A cylindrical catalyst having a diameter of mφ × a height of 10 mml and a central portion perforated was used.

As the filler 120, a Raschig ring having a diameter of 1/4 inch made of stainless steel was used.

(Experimental example)

In the case of a conventional catalyst tube in which only the catalyst is packed without mixing the filler 120, city gas is used as a raw fuel gas having a supply pressure of 1 kg / cm ² G using all of the catalyst tubes (30 tubes in the horizontal direction). When the reforming was carried out to supply a predetermined reforming rate (93%) by supplying to the tube, the differential pressure (pressure loss) of the entire catalyst tube was 0.6 kg / cm ² .

On the other hand, the reforming catalyst 110 and the filler 120 are mixed at a volume ratio of 2:
When the raw material gas of the same supply pressure and the same type is supplied to the catalyst tube 80 of the present invention in which the mixture is uniformly mixed to form the catalyst packed layer 130, and the inside thereof is filled, 21 tubes are horizontally As a result, the pressure difference in the catalyst tube 80 was about 0.6 kg / cm ² , and a predetermined reforming rate (93%) could be achieved.

From this, in the catalyst tube 80 of the present invention, pressure loss is reduced and gas flow is facilitated, and a predetermined reforming rate (93%) can be obtained as compared with a catalyst tube in which only the catalyst is packed in the tube. It can be seen that the heat transfer area can be reduced considerably by 30% [(30-21) /30=0.3] and the amount of catalyst can be reduced by about half [70% × (2/3) = 47%].

〔The invention's effect〕

As described above in detail, according to the present invention, in the reforming pipe of claim (1), a predetermined voidage is given to the reforming pipe, so that the gas flow resistance (pressure loss) is reduced and the gas flow rate is increased. And the heat transfer area can be reduced by increasing the heat transfer coefficient of the packed bed in the tube. Therefore, predetermined reforming can be performed by reducing the number of passes and the amount of catalyst in the reforming tube.

In the reforming tube of claim (2), in addition to the above-mentioned effects, since the reforming tube is horizontal, tube expansion due to heat,
Powdering of the catalyst due to shrinkage is prevented, and the life of the catalyst can be significantly extended. This horizontal reforming tube can have a remarkable advantage in the life of the catalyst particularly when it is used as a reformer whose operation and shutdown are performed relatively frequently, for example, a reformer for a fuel cell.

In the reformer according to claim (3), in addition to the effects of (1) and (2), since the heating of the horizontal reforming tube is performed by the fluidized bed, an efficient reforming operation can be performed. At the same time, the reforming tube is evenly heated to avoid local heating, and the life of the reforming tube and the catalyst can be extended. By making the reforming tube horizontal, the height of the fluidized bed can be reduced, the overall height of the apparatus can be reduced, and the power of the air blower can be reduced.

[Brief description of the drawings]

1 and 2 show the overall configuration of a fluidized bed reforming furnace as a reforming apparatus equipped with a reforming tube of the present invention. FIG. 1 is a vertical front view, and FIG. 2 is FIG. 3 (a) to 3 (f) are perspective views showing various examples of the packing used in the present invention, and FIG. 4 is a sectional view of the inside of the horizontal catalyst tube of the present invention. FIG. 2 is a cross-sectional view of a catalyst tube showing a state in which a catalyst packed layer in which a mixed catalyst and a filler are mixed is formed. 10: Furnace body, 10a: Furnace bottom, 20: Gas dispersion part, 30 ...
Air pipe, 40 …… Air dispersion pipe, 47 …… Air spout, 50 ……
Gas fuel pipe, 60 ... Gas fuel dispersion pipe, 62 ... Gas fuel injection port, 70 ... Flow chamber, 80 ... Catalyst pipe (reforming pipe), 90 ...
Exhaust gas outlet pipe, 100 fluidized medium, F fluidized bed, 110
... reforming catalyst, 120-125 ... packing, 130 ... catalyst packed bed.

Claims (3)

(57) [Claims] 1. A reforming pipe for reforming a hydrocarbon-based fuel by heating from the outside, comprising a reforming catalyst and a space having a required space ratio inside and having a good heat conductivity. And a catalyst-packed layer formed by uniformly mixing with a packing material made at a predetermined volume ratio, and being pressed by a pressing member to fill in a dense state, and having a predetermined space ratio therein. A reforming tube characterized in that the gas flow resistance has been reduced. 2. The reforming tube according to claim 1, wherein the reforming tube is a horizontal reforming tube. 3. A reforming catalyst for a hydrocarbon-based fuel and a metal filler having a space portion having a required space ratio and having good thermal conductivity are uniformly mixed at a predetermined volume ratio. The horizontal reforming tube, which has a catalyst packed layer formed by being pressed into a dense state by a pressing member and having a predetermined space ratio therein to reduce gas flow resistance, is formed by a fluidized bed. A reformer characterized by heating.