JPS59102804A - Device for modifying fuel - Google Patents

Abstract

PURPOSE:To obtain A compact device having good thermal efficiency, and the minimum starting and stopping time, by providing a modifying reactor with a catalytic layer of a double pipe and a fluidized hot layer for heating it in a steam reformer. CONSTITUTION:The air A for combustion fed to the air box 6 burns a fuel jetted from the burner 12, is made into a rising air flow, floats a fluid material to form the fluidized bed 1, makes temperature constant throughout the layer, and provides the catalytic pipe 2 with improved heat transfer. The pipe 2 is a double pipe, a ring-shaped part between the outer pipe 2 and the inner pipe 8 is packed with the catalyst 13, the raw material gas G1 to be modified is sent through a channel, flows as a rising flow, heat is transferred from the outer pipe 2 to the layer 1 during the gas flow, and the gas is kept at a high temperature required for modification reaction. The length of the pipe necessary for the heat transfer can be minimized extremely. The modified reaction gas G2 flows as a falling flow in the inner tube 8.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in hydrocarbon fuel reformers.

A fuel reforming system is a device that converts hydrocarbon fuel into gas whose main component is hydrogen, and has been used in large numbers in chemical plants.

The most typical type is the so-called steam refrigerating machine, which uses hydrocarbon fuels H and C as shown in Figure 1.
0l/(Steam is added and passed through the catalyst layer C under high temperature to produce a hydrogen-rich gas, and the remaining CO is converted to CO in a CO converter, and then CO is removed to produce a high-purity hydrogen-containing gas. In the figure, 1 is the catalyst tube, 2
3 is a device peripheral wall, and 3 is a burner. This conventional method had the following drawbacks.

(1) Since the catalyst tubes of steam reformers are used at high temperatures of 750°C or higher, even if high-temperature resistant materials are used, they are close to their usable limits, and even the slightest local increase in heat load or temperature imbalance may occur. If this occurs, the catalyst tube may overheat and explode, causing the gas inside to blow out. For this reason, the furnace was designed to keep the heat load very low and distribute it uniformly, making the furnace very large (and requiring a large amount of space), making it a very uneconomical design.

(2) The combustion exhaust gas that heated the catalyst tube is usually heat exchanged with water (steam) in a heat exchanger, but sufficient heat exchange is not always performed, and therefore the thermal efficiency is low (and uneconomical).

(3) Is the surrounding wall of the device made of fireproof material? Radiation from this refractory material is mainly used to heat the catalyst tubes, so it is difficult to control the temperature at partial loads, the minimum load is around 50%, and the rate of load change is small and limited. In addition to this, it also took a considerable amount of time to start up.

The purpose of the present invention is to eliminate the drawbacks of conventional ones and develop a higher performance and lower cost fuel reforming system.
In other words, (1) the overall dimensions are small and the area occupied is small, making it economical; (2) it effectively recovers heat from exhaust gas and has high thermal efficiency; (3) the start-up and stop times are minimized; (4) The purpose is to lower the minimum load sufficiently.

The present invention heats the catalyst using a fluidized bed, suppresses the maximum temperature of the heating source to below a certain value and makes it uniform, and uses double catalyst tubes to effectively recover heat, minimizing the need for external heat exchangers. At the same time, the thermal efficiency of the system is increased.The fuel reformer for steam reforming of hydrocarbon fuel is equipped with a double pipe catalyst layer and a fluidized heating layer for heating the catalyst layer. The present invention relates to a fuel reforming device comprising a reforming reactor.

The fuel reformer of the present invention will be explained in detail using FIG. 2 showing an example thereof. Figure 2 (IL) is shown in Figure 2 (1
1) B-B sectional view, Fig. 2 tb+ is Fig. 2 (A- of the river)
It is an A sectional view.

1 indicates a fluidized bed formed by fluidizing a fluid material such as sand or alumina (generally 40 to 200 microns). 2 is a double catalyst tube outer tube, and 3 is a reforming furnace vessel. Reference numeral 4 indicates an upper space of the fluidized bed, and 5 indicates a combustion exhaust gas outlet duct. 6
is a combustion air A-wind box that sends combustion air to the fluidized bed, 7 is a catalyst tube type logass horse-wind box, 8 is a double catalyst tube inner tube, and 9 is a reformed scum G!
The outlet nozzle 10 is a reformed gas output Roman manifold.

11 is a reformed gas outlet duct. 12 is a burner (pipe nozzle) arranged inside the fluidized bed. Figure 3 shows the details of the structure of the double catalyst tube, and Figure 3 (a)
) is a vertical sectional view, Figure 3 (bJ is a cc sectional view of (al),
FIG. 3(C) is a DD cross-sectional view of (al). 2 is an outer tube, 8 is an inner tube, and a catalyst 1 is placed in the annular part between them.
3 is filled. The catalyst used is vanadium, nickel, etc., and its shape is 5 to 6 fl.
An example is a pipe-shaped one with an outer diameter of 16 m and a height of about 19 mm. 14 is a catalyst holding porous plate or mesh plate attached to the outer surface of the inner tube, 15 is a guide vane installed at the top of the double tube, and 16 is a ribbon for promoting heat transfer installed with MnC inside the inner tube. It is. 17 is an outer tube holding plate;
18 is an inner tube holding plate.

Next, the functions and effects of the present invention will be explained.

The air A supplied to the combustion air box 6 shown in FIG. 2 burns the fuel injected from the burner 12, and becomes an updraft to float the fluidized material and form a fluidized bed 1, which is uniform throughout the layer. temperature and good heat transfer to the catalyst tubes 2. The fluidized bed is just formed on the upper surface of the catalyst tube, and in the upper space 4 of the fluidized bed above the fluidized bed, the cross-sectional area increases rapidly and the superficial velocity rapidly increases, so that a so-called carryover occurs in which the fluidized material is carried away by the rising air. The phenomenon can be minimized and therefore the replenishment of fluid material can be minimized. By arranging a large number of burners 12 at the bottom of the fluidized bed, it is possible to achieve a pressure that enables rapid startup and to minimize the temperature distribution within the bed. G is combustion exhaust gas.

FIG. 3 shows the internal structure of the double catalyst tube as described above, in which the annular part between the outer tube 2 and the inner tube 8 is filled with catalyst, and the raw material to be reformed is Gas G1 flows upward through the reactant gas inlet passage from below to above. At this time, heat is transferred from the outer tube by the fluidized bed to maintain the high temperature necessary for the reforming reaction. The heat transfer coefficient by fluidized bed is 200~
250"-7m" hc is expected, and the tube length required for heat transfer can be made extremely small.

The hydrocarbon fuel gas that has passed through the catalyst layer is gradually reformed into a gas whose main components are hydrogen and carbon monoxide, and then reaches the double pipe section. As shown in FIG. 3 tc+, in the double tubing section, guide plates 715 are radially attached to the inside of the outer tube so as to connect with the tip of the inner tube. The hydrogen-rich gas that has ascended through the ring can smoothly change direction and move to the inner tube. At the same time, in order to make the most of the effect of convective transmission due to one-way collision conversion, the heat transfer area can be increased by means of fins (not shown) provided on the inner wall of the outer tube and/or the outer wall of the inner tube. The reactant gas G, which has been reformed to be rich in hydrogen, flows in a downward flow inside the inner tube 8. Hydrogen-rich gas has better heat transfer than hydrocarbon gas, so this effect should be maximized (5US304 etc.). A heat accelerating ribbon 16 made of a high temperature resistant material is installed to increase the unit heat transfer amount and the heat transfer area. 14 is a catalyst holding perforated plate having a large number of holes. Composed of plates or mesh plates, this prevents catalysts that have deteriorated over many years of use from being crushed or powdered and settling at the bottom of the double tube, causing problems such as channel pollution and blockage. Inspection and replacement of the catalyst can be easily carried out by removing the inner tube holding grate 18 and pulling out the inner tube 8 downward.

FIG. 4 shows the temperature distribution of the dual catalyst tube, showing the fluidized bed temperature A, the outflow fluid temperature B, and the return fluid temperature C as a function of the catalyst tube position. This figure also shows that the reactant gas, which was at 850°C at the top, drops to 700°C at the outlet, thereby acting as an effective heat transfer device that simultaneously preheats the inlet fluid.

In the above description, the lower end of the double catalyst tube is supported and the upper end is free, but it is of course possible to change the direction of this structure by 180° and suspend it from the upper part, leaving the lower end free.

Further, the fluidized bed can be either a normal pressure fluidized bed or a pressurized fluidized bed.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing the structure of a reaction section in a conventional fuel reformer, and FIG. 2 (aJ is a longitudinal sectional view of the combustion reformer of the present invention, FIG. 2 (1)) A-A in Figure 2 ta)
FIG. Does Fig. 3(a) correspond to the present invention? FIG. 3 is a vertical cross-sectional view showing the structure of a double-tube catalyst layer in
Fig. 3(C) is a cross-sectional view taken along line c-c in Fig. 3(a).
It is a DD sectional view of. FIG. 4 is a graph showing the temperature distribution in the double tube catalyst layer of the present invention. Sub-agents 1) Meikoku agent Ryo Hagihara - Figure 1 Ox Figure 3 (C) 'tcr2 Figure 4 □ Temperature 0C

Claims (2)

[Claims] (1) A fuel reformer for steam reforming of hydrocarbon fuel Kj6, which is a fuel reformer consisting of a steam reforming reactor provided with a double pipe catalyst layer and a fluidized heating bed for heating the catalyst layer. quality equipment. (2) A holding porous plate for supporting the catalyst layer is provided on the outer wall of the double-pipe inner tube of the double-pipe catalyst layer, a guide vane for rectifying flow and promoting heat transfer is provided at the top, and a ribbon for promoting heat transfer is provided inside the inner tube. The fuel reformer according to claim 1, wherein the fuel reformer is provided with: