JP3356310B2 - Raw material supply method for reformer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for supplying raw materials to a reformer for a fuel cell power plant.

[0002]

2. Description of the Related Art A fuel cell power generation plant is a power generation device that electrochemically generates electricity from a fuel containing hydrogen. When a raw fuel gas such as natural gas is used as a fuel, the raw fuel gas contains hydrogen. A reformer is used to reform into a reformed gas. In such a reformer, hydrocarbons (for example, methane, CH ₄ ) contained in the raw fuel gas are reacted with steam (H ₂ O), and hydrogen (H ₂ O) is reacted by, for example, CH ₄ + H ₂ O → CO + 3H ₂ . ₂ ) and converted (reformed) into carbon monoxide (CO). Therefore, before supplying the raw fuel to the reformer, it is necessary to supply the raw fuel with an amount of steam required for the above-described reforming reaction.

[0003] Conventional raw material supply to the reformer is, for example, as shown in FIG.
As shown in (1), reforming steam g is mixed with the raw fuel gas a via a flow control valve b (referred to as an S / C control valve), and the temperature is further increased by a heater c to obtain a reformer raw material gas d. It was sent to the reformer e.

[0004]

However, in the conventional feed of the reformer, the raw fuel gas a at normal temperature and the high-temperature reforming steam g are not ideally mixed with each other. There is a problem that water condensation occurs locally and water droplets are generated. Once this water droplet is formed, the heater c after mixing,
Since the raw material gas d passes in a short time, it cannot be re-evaporated, and this water droplet enters the reformer e, and there is a problem that the reforming catalyst in the reformer is damaged or deteriorated.

In order to avoid such a problem, that is, to avoid condensation of water when mixing steam, conventionally, it was necessary to use steam having a high degree of superheat. However, in a fuel cell power plant, since steam is generated by using exhaust heat of the plant, there is a problem that high-temperature exhaust gas is required to obtain steam having a high degree of superheat. The present invention has been made to solve such a problem. That is, an object of the present invention is to provide a raw material supply method for a reformer that does not generate water droplets at the time of mixing of steam, and thus does not damage or deteriorate the reforming catalyst due to the water droplets and does not require steam having a high degree of superheat. To provide.

[0006]

According to the present invention, carbonization by heating steam having a pressure equal to or higher than the saturation pressure of reforming steam is performed.
Indirect heating of the reforming raw fuel gas comprising hydrogen , then mixing of the reforming steam into the raw fuel gas to form a reforming raw material gas, and then indirectly heating the reforming raw material gas to form a reformer Supply method for a reformer.

According to a preferred embodiment of the invention, the heating steam to the indirect heat raw fuel gas for the reforming, reforming
Reforming steam before depressurization to supply to the vessel .

[0008]

According to the present invention, a heater (heat exchanger) for indirectly heating a raw fuel gas for reforming with steam having a pressure equal to or higher than the saturation pressure of steam for reforming is used as the raw fuel gas. By providing it before injecting the reforming steam, the condensation of moisture in the reformer raw material gas is prevented.

That is, according to the present invention, the raw fuel gas for reforming is indirectly heated by the heating steam having a pressure higher than the saturation pressure of the steam for reforming.
Is higher than the saturation temperature of the reforming steam, and the raw fuel gas is heated to a temperature close to or higher than the saturation temperature of the reforming steam before being mixed with the reforming steam. Therefore, heating
Even if the reforming steam reduced in pressure to supply the steam for reforming to the raw fuel gas heated to a temperature close to (or higher than) the saturation temperature of the reforming steam, the steam temperature almost drops Therefore, there is no generation of water droplets when mixing steam, and there is no damage or deterioration of the reforming catalyst due to water droplets. Also,
The heating steam for indirectly heating the raw fuel gas is supplied to the reformer.
In order to supply the steam, it is sufficient that the steam has a pressure equal to or higher than the saturation pressure of the reforming steam before the pressure reduction , and steam having a particularly high degree of superheat is not required.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram showing a raw material supply system of a reformer for implementing the method of the present invention. In this figure, a raw fuel 1 (hydrocarbon such as natural gas) for reforming is supplied from a raw fuel supply line to a steam-heated heater 2. , And reformed as a raw material gas 5, passed through a raw material gas line of a reformer, further heated by a raw material gas preheater 6, and then filled with a catalyst of a reformer 7. Enter into the reforming tube. In the reformer 7, the fuel 8 and the air 9 are supplied to the reformer combustor 10 to burn the fuel 8, and the heat generated by the combustion causes the reformer raw material gas 5 in the reforming pipe to act as a catalyst. Is reformed into a reformed gas 11 containing hydrogen (H2) and carbon monoxide (CO) as main components, and supplied from a reformed gas line to a fuel cell or the like. Also, the combustion exhaust gas 12 generated by combustion
Is discharged from the reformer combustion exhaust gas line to the outside of the reformer.

Reference numeral 13 denotes a steam supply line. In a fuel cell power plant, steam generated by recovering exhaust heat in the plant is used. The flow control valve 14 is a control valve for supplying a fixed amount of water vapor to the carbon content in the raw fuel (that is, keeping the steam / carbon ratio constant). The reforming steam 4 is mixed into the raw fuel 1 by the flow control valve 14. Reference numeral 15 denotes steam for heating of the steam heating type heater 2, and condensed water condensed in the heater 2 is discharged out of the system via a condensed water line 16.

The feed of the raw material of the reformer is performed by using the steam 4 for reforming.
The raw fuel gas 1 for reforming is indirectly heated by the heating steam 15 having a pressure equal to or higher than the saturation pressure.
The reduced-pressure reforming steam 4 is mixed into the raw fuel gas 1 to form a reforming raw material gas 5, which is then indirectly heated by a raw gas preheater 6 and supplied to the reformer 7. This is done by: In the illustrated example, the heating steam 15 for indirectly heating the raw fuel gas 1 is the same as the reforming steam 4, but the present invention is not limited to this, and the pressure of the reforming steam 4 is different from that of the reforming steam 4. May be used as the heating steam 15 of the steam heating heater 2. Further, the raw material gas preheater 6 is of a steam heating type similar to the heater 2, but is preferably preheated with steam at a higher pressure.

According to the above-described method of the present invention, the raw fuel 1 from the raw fuel supply line is changed in saturation pressure and therefore in saturation temperature.
Since the steam for heating 15 higher than the steam for quality is used to heat the steam to the saturation temperature of the steam for reforming 4 or a temperature close to the saturation temperature of the steam for reforming 4 and then mixed with the steam 4 for reforming, In 5, there is no possibility that moisture in the reformer raw material gas will condense. For this reason, there is no possibility that the water droplets flow into the reformer and cause various problems such as destruction of the reforming catalyst. Further, the steam for indirectly heating the raw fuel gas may be steam having a pressure equal to or higher than the saturation pressure of the reforming steam, and does not require steam having a particularly high degree of superheat.

Further, the steam side of the steam type heater 2 is a condensing heat transfer and has an extremely high heat transfer coefficient, and heats the raw fuel 1 to a temperature near the saturation (condensation) temperature of the heating steam with a relatively small heat transfer area. be able to.

[0015]

Thus, according to the present invention, there are provided: 1. When raw fuel such as natural gas and steam for reforming are mixed, there is no generation of water droplets due to the delay of steam even locally. As a result, there is no possibility that water droplets will flow into the reformer and cause problems such as damage to the catalyst. It is also possible to use low-superheated or saturated steam as the reforming steam, and it is possible to generate the reforming steam by using the relatively low-temperature exhaust heat, thereby improving the exhaust heat recovery efficiency. Can do it 4. Since steam is used as the raw fuel heating heat source, the condensing heat transfer coefficient is high, so that various effects can be obtained, such as the steam heating type heater can be downsized.

In summary, according to the present invention, there is no generation of water droplets at the time of mixing steam, and therefore, there is no damage or deterioration of the reforming catalyst due to the water droplets, and there is no need for high superheated steam. A method can be provided.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a raw material supply system of a reformer for implementing a method of the present invention.

FIG. 2 is a configuration diagram showing a raw material supply system of a conventional reformer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Raw fuel 2 Steam heating type heater 4 Reforming steam 5 Reformer raw material gas 6 Raw material gas preheater 7 Reformer 8 Reformer fuel 9 Air 10 Reformer combustor 11 Reformed gas 12 Reformer Combustion exhaust gas 13 Steam supply line 14 Flow control valve 15 Steam for heating 16 Condensed water line

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01M 8/04-8/06 C01B 3/38

Claims (2)

(57) [Claims] 1. A saturated pressure above the pressure of the steam reforming pressure
The reforming raw fuel gas composed of hydrocarbons is indirectly heated by the steam for heat, and then the reforming steam is mixed into the raw fuel gas to form a raw material gas for reforming, and then the raw material gas for reforming is heated indirectly. And supplying the raw material to the reformer. 2. The indirect heating of the raw fuel gas for reforming
2. The method according to claim 1, wherein the heating steam is reforming steam before the pressure is reduced to supply the steam to the reformer. 3.