JPS6125643B2 - - Google Patents

Description

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

A fuel reformer is a device that converts hydrocarbon fuel into gas whose main component is hydrogen, and has been used in many chemical brands. The most typical one is the so-called steam refrigerant, and as shown in Figure 1, it uses hydrocarbon fuel H.
Add water vapor to C. and apply it to catalyst layer C under high temperature.
The remaining CO is converted into CO ₂ using a CO converter, and then the CO ₂ is removed to produce a highly pure pure element-containing gas. In the figure, 1 is a catalyst tube, 2 is a peripheral wall of the device, and 3 is a burner. This conventional method had the following drawbacks.

(1) Since the catalyst tube 1 of the steam reformer is used at high temperatures of 750°C or higher, even if high-temperature resistant materials are used, it is close to its usable limit, and even the slightest local increase in heat load or temperature unsteadiness may occur. If there was an imbalance, the catalyst tube would overheat and blow out, causing the gas inside to blow out. For this reason, the furnace design has been designed to keep the heat load very low and uniformly distributed, resulting in a very large furnace size and a large space requirement, resulting in 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 carried out, and therefore the thermal efficiency is low and uneconomical.

(3) The peripheral wall 2 of the device is made of refractory material, and the radiation from this refractory material is mainly used to heat the catalyst tubes. Therefore, it is difficult to control the temperature at partial loads, and when the lowest load In addition, the speed of load change was limited to a small value, and it took a long time to start up.

(4) The combustion furnace of the reformer was designed to operate at normal pressure, so it was very large in size, and because it was under negative pressure, an induced draft fan (IDF) was required.

The present invention aims to eliminate the drawbacks of the conventional ones and develop a fuel reforming system with higher performance and lower cost, namely: (1) It is economical with a small overall size and a small footprint; , (2) To effectively recover heat from exhaust gas and have high thermal efficiency, (3) To minimize startup and shutdown times, and (4) To sufficiently lower the minimum load.

The present invention uses a pressurized fluidized bed to heat the reforming furnace, thereby making the entire structure extremely compact.
In addition, the wall thickness of the catalyst tube is reduced to reduce thermal stress, and it is also lightweight and economical, making it easy to modularize and transport by trailer. In a fuel reformer that converts into hydrogen-rich gas through a forming reaction, a pressurized fluidized bed is used as the heating medium, a reactor with a double-tube catalyst tube, and a gas turbine driven by the combustion exhaust gas from the reactor are used. The present invention relates to a fuel reformer provided therein.

The material of the pressurized fluidized bed serving as the heating medium of the present invention is a sand or alumina-based material with a size of about 40 to 200μ, and the degree of pressurization is above atmospheric pressure, 20 to 30 ata.
In general, around 4ata is commonly used. In the double-pipe catalyst tube, the annular part between the outer tube 4 and the inner tube 5 is filled with a vanadium nickel catalyst, which is generally pipe-shaped (inner diameter 5 to 6 mm, outer diameter 16 mm, height 19 mm, etc.). The raw material gas to be reformed flows from the bottom to the top through the catalyst-packed section, and a reaction occurs with the heat from the pressurized fluidized bed. The hydrocarbon fuel gas that has passed through the catalyst layer is reformed into a gas whose main components are hydrogen and carbon monoxide, which reaches the top of the double tube and is taken out through the inner tube.

The fuel reforming system of the present invention can be applied not only to fuel reformers but also to fluidized bed heat exchangers and the like.

An example of the configuration of the system of the present invention is shown in FIG.

1 is a pressurized reforming furnace vessel, 2 is a fluidized heating bed, 3
4 is an outer tube of a double catalyst tube, and 5 is an inner tube of a double catalyst tube. 6 is a fuel exhaust gas outlet duct, 7 is a gas turbine, 8 is a gas turbine exhaust duct, 9 is an exhaust heat recovery boiler, and 10 is a chimney.

11 is a hydrocarbon fuel HC supply pipe, 12 is a burner fuel pipe (burner 12' is a pipe nozzle), 1
3 is a raw material gas pipe for reforming, 14 is a raw material gas-steam mixing device, and 18 is a raw material gas/steam mixed gas pipe. 15 is a boiler water supply pipe, 16 is a boiler water supply pump, and 17 is a reforming steam pipe. 19 is a reaction product gas pipe, 20 is a heat exchanger, 21 is a CO shift converter inlet pipe, and 22 is a CO shift converter. 23 is a combustion air compressor A, 24 is a combustion air duct, 25 is a combustion air box, and 26 is a generator.

A pressurized reforming furnace vessel 1 is constructed by a pressurized fluidized heating bed 2 formed by burning fuel from a burner 12' with air from a line 18 to raise a fluidized material, and a double catalyst tube 4 and 5 is heated uniformly and at a constant temperature, and the mixture supplied through the raw material gas/steam mixture gas pipe 18 is reformed by the catalyst bed filled therein, so that hydrogen and carbon monoxide are the main components. This gas is sent out of the furnace from the reaction product gas pipe 19. The temperature of the reaction product gas is lowered to an appropriate temperature in a heat exchanger 20, and then reformed into carbon monoxide in a CO shift converter 22 (CO+H ₂ O→CO ₂ +H ₂ ), which is used as H ₂ rich gas H.

The exhaust gas generated by combustion in the fluidized bed passes through the fluidized bed upper space 3, the combustion exhaust gas duct 6,
Enter gas turbine 7. A compressor 23 and a generator 26 are connected to this gas turbine.
After the combustion air is pressurized to a required pressure by the compressor 23, it is supplied to the fluidized bed via the combustion air duct 24 and the combustion air box 25. The surplus power supplied to the compressor is converted into electric power by the generator 26. The exhaust gas that has worked in the gas turbine undergoes heat exchange in an exhaust heat recovery boiler 9, and then is released into the atmosphere from a chimney 10. This feed water for the exhaust heat recovery boiler is sent by a feed water pump 16, turned into steam by 9, and mixed with raw material gas by a raw material gas/steam mixer 14.

Adoption of a pressurized fluidized bed provides the following advantages.

(1) The superficial velocity becomes smaller compared to normal pressure. Alternatively, by matching the superficial velocity, the bed area can be reduced and the overall size can be made very small.

(2) When the superficial velocity is kept small, the diameter of the fluidized material can be made that much smaller, and therefore the wear of the catalyst tube inserted in the bed is small, and the carryover in the upper space is also small.

(3) Higher fluidized bed heat transfer coefficients can be obtained by pressurization.

(4) The energy contained in the high-temperature exhaust gas is recovered as power by the gas turbine, which not only covers the power required for the compressor, but also enables direct power generation from the surplus. Moreover, the exhaust heat recovery boiler can be made smaller accordingly.

(5) The reformer container, which is the heaviest item, can be made compact, making transportation and installation extremely easy, and modularization allows for easy trailer transportation.

(6) Since the temperature inside the fluidized bed is uniform and constant, by controlling this temperature it is possible to reliably prevent blowout accidents of catalyst tubes that are placed under severe temperature conditions, and to maintain the temperature of the fluidized bed. It also allows you to take advantage of its excellent partial load characteristics and large load change speed.

[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 is a flow sheet showing an example of the fuel reforming system of the present invention.

Claims (1)

[Claims] 1. In a fuel reformer that converts hydrocarbon fuel into hydrogen-rich gas by a steam reforming reaction, a pressurized fluidized bed is used as the heating medium, a reactor using a double pipe between catalysts, and a A fuel reformer equipped with a gas turbine driven by combustion exhaust gas.