JP2003132918A - Fuel cell generating system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell generating system that enhances combustion efficiency in a combustion portion. SOLUTION: This fuel cell generating system has a reforming apparatus 7 that forms reformed gas G from fuel gas X, a feed water supply line 9 that supplies feed water Y required in water vapor reforming reaction to the reforming apparatus 7, a combustion portion 10 that heats the reforming apparatus 7 by the use of feed fuel gas F supplied through a feed fuel gas supply line 11, an electrolytic type fuel cell 1 that holds an electrolytic film between a pair of electrodes consisting of a fuel pole 3 and an oxidizer pole 2 and generates electricity by the use of reformed gas G supplied to the fuel pole 3 and oxidizer gas A supplied to the oxidizer pole 2, an off-gas discharge line 12 that joins off-gas g discharged from the fuel pole 3 in the electrolytic type fuel cell 1 into the feed fuel gas supply line 11, a trap 16 that is arranged in the off-gas discharge line 12 and drains condensed water D from off-gas g flow and a condensed water drainage line 35 that joins condensed water drained from the trap 16 into the feed water supply line 9.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a treatment and countermeasure for condensed water generated in a fuel cell power generation system including a reformer and an electrolyte fuel cell. Related to the fuel cell power generation system performed. 2. Description of the Related Art A conventional fuel cell power generation system is disclosed, for example, in Japanese Patent Application Laid-Open No. 2001-155748. FIG. 4 shows the fuel cell power generation system disclosed herein. The solid polymer electrolyte fuel cell 1 includes an oxidizer electrode 2 and a fuel electrode 3 with a solid polymer electrolyte membrane interposed therebetween. Oxidizer electrode 2
For example, air is supplied as the oxidant gas A through the oxidant supply path 4. When the supplied air flows downstream through a predetermined passage in contact with the oxidant electrode 2, a necessary amount of oxygen in the air undergoes an electrode reaction and is consumed, and the remaining gas a passes through the remaining gas discharge passage 5. It is discharged outside. [0003] The upstream side of the fuel electrode 3 is connected to a reformer 7 via a reformed gas supply path 6. The reformer 7 is supplied with a fuel gas X such as natural gas through a fuel gas supply passage 8 and a raw water Y required for a steam reforming reaction through a raw water supply passage 9. The reformer 7 includes a combustion unit 10 for heating itself. The raw fuel gas F is supplied to the combustion unit 10 through a raw fuel gas supply path 11. When the raw fuel gas F is burned in the combustion section 10, a steam reforming reaction between the fuel gas X and the raw water Y occurs in the reformer 7, and a hydrogen-rich reformed gas G is generated. The reformed gas G generated by the reformer 7 is supplied to the fuel electrode 3 via the reformed gas supply passage 6 and flows downstream through a predetermined passage in contact with the fuel electrode 3 when the reformed gas G is generated. The required amount of hydrogen in the electrode reacts and is consumed, and the remaining off-gas g is combined with the raw fuel gas F flow in the raw fuel gas supply path 11 via the off-gas discharge path 12. Although not disclosed in the above-mentioned prior art publication, a heat exchanger for lowering the temperature of the reformed gas G is disposed in the reformed gas supply passage 6. The heat exchanger lowers the temperature of the reformed gas from the high operating temperature of the reformer 4 to the low operating temperature of the electrolyte fuel cell 1. In the above conventional fuel cell power generation system, condensed water is supplied to the combustion section together with off-gas. Therefore, there is a problem that the combustion efficiency of the combustion section is low. Therefore, a technical problem of the present invention is to provide a fuel cell power generation system in which the combustion efficiency of a combustion section is increased. [0007] The technical means of the present invention taken to solve the above-mentioned technical problems is to provide a reformer for generating a reformed gas from a fuel gas, and a steam reforming reaction. Water supply path for supplying raw water necessary for the reformer to the reformer, a combustion section for heating the reformer using raw fuel gas supplied through the raw fuel gas supply path, a fuel electrode and an oxidizer An electrolyte type fuel cell in which an electrolyte membrane is sandwiched between a pair of electrodes composed of electrodes, and generates electricity using a reformed gas supplied to a fuel electrode and an oxidizing gas supplied to an oxidizing electrode, and an electrolyte. Exhaust gas that joins the off-gas discharged from the fuel electrode of the fuel cell to the raw fuel gas supply path, a trap that is arranged in the off-gas discharge path and drains condensed water from the off-gas stream, and condensed water that is drained from the trap Into the feed water supply channel A fuel cell power generation system comprising: a drainage drainage channel; DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an off-gas discharge passage for combining an off-gas discharged from a fuel electrode of an electrolyte fuel cell with a raw fuel gas supplied to a combustion section, and condensed water from the off-gas stream. It has a trap to drain. Therefore, off-gas from which condensed water has been removed by the trap is supplied to the combustion section, and the combustion efficiency of the combustion section is increased. Further, in the present invention, the condensed water discharged from the trap is joined to a raw water supply passage for supplying raw water necessary for the steam reforming reaction to the reformer. Therefore, the condensed water separated from the off-gas stream is reused as raw water necessary for the steam reforming reaction, and the operation efficiency of the fuel cell power generation system is improved. An embodiment showing a specific example of the above technical means will be described with reference to FIGS. 1 to 3. FIG. 1 is a diagram showing a configuration of a fuel cell power generation system according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of the trap of FIG. 1, and FIG. 3 is a cross-sectional view of FIG. In FIG. 1, the same components as those of the prior art shown in FIG. 4 are denoted by the same reference numerals, and detailed description will be omitted. The temperature of the reformed gas G is supplied to a reformed gas supply path 6 for supplying the reformed gas G from the reformer 7 to the fuel electrode 3 of the electrolyte fuel cell 1. A heat exchanger 13 is provided for cooling from 700 ° C. to about 80 ° C., which is the operating temperature of the electrolyte fuel cell 1. The heat exchanger 13
This is a water heat exchanger that cools the reformed gas G with the cooling water W. A trap 15 for discharging condensed water D from the reformed gas G flow is disposed on the reformed gas outlet 14 side of the heat exchanger 13. A trap 16 for draining condensed water D from the off-gas g flow is disposed in the off-gas discharge path 12. A trap 17 for draining condensed water D from the remaining gas a stream is provided in the remaining gas discharge path 5. The traps 15, 16, 17 are float traps having a built-in steam-water separation unit. The traps 15, 16, and 17 are shown in FIGS.
Shown in The casing of the trap is formed by welding an upper body 21 made of a stainless steel thin plate into a cylindrical shape and a lower body 22 made of a stainless steel thin plate into a substantially hemispherical shape at the mating surfaces. An inlet 24 for introducing a mixed flow of gas and condensed water is attached to an upper side surface of the upper body 21. The gas outlet 31 is coaxial with the inlet 24 of the upper body 21.
Is attached. Disc-shaped water / water separation plates 32 and 33 as a water / water separation unit are respectively attached to the inlet 24 and the outlet 31 on the valve chamber 23 end. A valve chamber 23 is formed inside the casing,
A spherical closed float 26 is arranged in the valve chamber 23 in a free state. The lower body 22 is provided with a float seat 25 for sitting when the float 26 descends. The float seat 25 is formed in two protruding shapes toward the inside of the valve chamber 23 in parallel with the central axis of the valve port 27 which is opened and closed by the floating movement of the float 26 and extending in the parallel direction. At a position facing the float seat 25 of the lower main body 22, a through hole 30 is provided as a mounting portion for mounting a valve seat member 29 provided with a valve port 27 and a drain port 28 to the lower main body 22. The mixed flow of the gas and the condensed water flowing into the valve chamber 23 from the inlet 24 first collides with the steam-water separating plate 32 on the inlet side to perform the first-stage steam-water separation. The water drops downward, while the gas having a small mass does not drop, but again collides with the steam-water separator 33 on the outlet 31 side to perform the second-stage steam-water separation. The gas separated from the condensed water by the two-stage steam-water separation is exhausted from the outlet 31. The liquid that has dropped downward accumulates in the valve chamber 23,
The liquid level gradually rises to raise the float 26 by its buoyancy (the position shown by the broken line in FIG. 2), and the float 26 is separated from the float seat 25 and the valve port 27 to thereby provide the valve chamber 2
The condensed water in 3 is drained from the drain 28. When the condensed water is drained and the liquid level in the valve chamber 23 drops, the float 26
Descends and sits on the float seat 25 and the valve port 27, thereby preventing gas from leaking from the drain port 28. The condensed water D drained from the drain port 28 of the trap 15 passes through a condensed water drain channel 34, and the condensed water D drained from the drain port 28 of the trap 16 is condensed water drain channel 35.
, The condensed water D drained from the drain port 28 of the trap 17 is joined to the raw water Y flow in the raw water supply passage 9 via the condensed water drain passage 36. Since the off gas g from which the condensed water has been removed is exhausted from the outlet 31 of the trap 16, the combustion efficiency of the combustion unit 10 can be increased. Trap 1
Since the condensed water D drained from the drain port 28 of No. 6 is combined with the raw material water Y and reused, the operation efficiency of the fuel cell power generation system can be improved. The condensed water D drained from the drain ports 28 of the traps 15 and 17 may be drained out of the system, but can be reused by being combined with the raw material water Y flow. Exit 3 of trap 15
Since the reformed gas G from which condensed water is removed is exhausted from the fuel cell 1, the power generation efficiency of the electrolyte fuel cell 1 can be increased. According to the present invention, as described above, the condensed water is drained from the off-gas stream, and the off-gas from which the condensed water has been removed is supplied to the combustion section, thereby improving the combustion efficiency of the combustion section. In addition, the condensed water separated from the off-gas stream is combined with the raw water supply path and reused, thereby providing an excellent effect that the operation efficiency of the fuel cell power generation system can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing a configuration of a fuel cell power generation system according to an embodiment of the present invention. FIG. 2 is a sectional view of the trap of FIG. 1; FIG. 3 is a sectional view taken along line AA of FIG. 2; FIG. 4 is a diagram showing a configuration of a conventional fuel cell power generation system. [Description of Signs] 1 polymer electrolyte fuel cell 2 oxidant electrode 3 fuel electrode 4 oxidant gas supply path 5 remaining gas discharge path 6 reformed gas supply path 7 reformer 8 fuel gas supply path 9 feed water Passage 10 Combustion unit 11 Raw fuel gas supply passage 12 Off gas discharge passage 13 Heat exchanger 14 Reformed gas outlets 15, 16, 17 Trap 23 Valve chamber 24 Inlet 25 Float seat 26 Float 27 Valve outlet 28 Drain outlet 31 Exit 32 Steam Separation plate 33 Steam-water separation plates 34, 35, 36 Condensate drainage channel

Claims (1)

Claims: 1. A reformer for producing a reformed gas from a fuel gas, a raw water supply path for supplying raw water required for a steam reforming reaction to the reformer, and a raw fuel gas. A combustion unit for heating the reformer using the raw fuel gas supplied through the supply path,
An electrolyte type in which an electrolyte membrane is sandwiched between a pair of electrodes consisting of a fuel electrode and an oxidant electrode, and generates power using a reformed gas supplied to the fuel electrode and an oxidant gas supplied to the oxidant electrode. A fuel cell, an off-gas discharge path that joins the off-gas discharged from the fuel electrode of the electrolyte fuel cell to the raw fuel gas supply path, a trap that is disposed in the off-gas discharge path, and that drains condensed water from the off-gas flow; A fuel cell power generation system, comprising: a condensed water drainage passage for joining condensed water discharged to a raw water supply passage.