JPS6347228B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel processing device for reforming and converting raw materials such as natural gas through steam reforming, carbon monoxide conversion, etc. to produce fuels such as hydrogen gas; The present invention relates to a fuel cell power generation system comprising a fuel cell device that generates power by receiving supply of fuel and an oxidizing agent such as air, and a fuel cell device including its auxiliary equipment, and particularly relates to a method of stopping the system during its startup process.

Generally, when stopping a plant during plant operation, the stop mode is often changed based on the reason and conditions for the stop, but when the organic start-up operation of each component is not satisfied during the start-up process of the plant, Unlike during operation, the engine is still in its early stages, so it is normal to perform a stop operation in a single stop mode.

By the way, in a fuel power generation system that handles flammable gas, the system is purged or replaced with an inert gas when it is shut down, but the system is also preheated with an inert gas during the startup process. It will be done. Therefore, when the system is stopped during the startup process, if a single stop mode is used, inert gas is injected for preheating, purged, and then inert gas is immediately reinjected for shutdown. There are disadvantages in that unnecessary operations such as these are performed, and that the stop time is unnecessarily prolonged based on the longest conditions.

In addition, when preparing multiple stop modes for the fuel processing device and the fuel cell device and trying to stop them individually, the stop conditions for both devices are different, so when programming a series of stop operations, it is necessary to The relationship between time and time becomes complicated, and conditions tend to be duplicated or missing, making program creation extremely troublesome.

Therefore, the present invention provides the following advantages when stopping the fuel cell power generation system of the type described at the beginning during the startup process.
It is an object of the present invention to provide a stopping method that can be stopped in a shorter time and without requiring unnecessary operations than in the past, and that allows a simpler stopping operation program.

According to the present invention, the purpose of this is to divide the stop modes of the fuel processing device and the fuel cell device into two specific stop modes each, and select these specific stop modes based on switching conditions specific to each device. This is achieved by a stopping method that automatically selects the stoppage method. That is, according to the method of the present invention, the method includes an inert gas purge means, a water vapor purge means, and an inert gas preheating means for starting. , a fuel processing device for reforming and converting raw fuel to produce fuel, an inert gas purge means, and a start-up inert gas preheating and oxidizing gas heating means, and supplying the fuel and the oxidizing agent. 2. A method of operating a fuel cell power generation system comprising a fuel cell device that receives electricity and generates electricity, wherein as a stop procedure after steady operation of the system, the fuel processing device performs a water vapor purge, then an inert gas purge, and then performs a predetermined operation. The fuel cell device performs a predetermined valve operation after stopping the oxidizing gas heating, performs an inert gas purge, and then performs a predetermined valve operation, and as a startup procedure of the system, the fuel processing device In the operating method of a fuel cell power generation system including a step of performing a steam purge after preheating, and supplying reformed gas after heating by the heating means, the fuel cell device performs a stop procedure in the startup process of the fuel processing device using the steam purge. Switching is done depending on the conditions before and after the start of purge. Before the start of steam purge, the inert gas preheating procedure is stopped, and after the start of steam purge, the inert gas purge is performed after steam purge, and then the specified valve operation is performed in the same way as the stop procedure after steady operation. and switching the stopping procedure in the startup process of the fuel cell device depending on the conditions before and after the start of heating by the heating means,
Before the start of heating, a predetermined valve operation is performed, and after the start of heating, the procedure is to perform an inert gas purge after stopping the oxidant gas heating, and then perform a predetermined valve operation, similar to the stop procedure after steady operation.

This makes it possible to efficiently stop the entire system with the same system stop command.

Other objects or preferred embodiments of the invention will become apparent in the following description of embodiments of the invention.

FIG. 1 is a basic system diagram of an embodiment of the present invention.

In FIG. 1, numeral 10 shown on the right side of the drawing is a hydrogen-oxygen (air) type fuel cell, which includes a fuel chamber 11, an oxidizer (air) chamber 12, electrodes 13 and 14, and an electrolyte chamber or an electrolyte-impregnated matrix. 15
It consists of The air chamber 12 includes an air source 1
Air is supplied from 6 through a blower 17.
Items numbered in the 100s, 200s, and 300s are valves, and their operations will be described later. Air is supplied by blower 18 when starting up the fuel cell and when operating as necessary.
A part of the air is circulated through the startup air heater 19 and maintained at a predetermined temperature. The startup air heater 19 corresponds to inert gas preheating and oxidant gas heating means for startup, and when starting with the inert gas purged,
The burner of the heater 19 is ignited to preheat the inert gas, and soon air is introduced and heated. The fuel chamber 11 is supplied with a fuel gas containing a large amount of hydrogen obtained by steam reforming the raw material gas. The modification process is as follows.

First, natural gas containing methane gas as a main component is used as the raw material gas, but in order to remove the sulfur content that causes a decrease in the activity of the reforming catalyst, hydrogen ( For example, a portion of hydrogen-containing gas from a steam/water separator 49 (to be described later) is added and sent to the desulfurization reactor 24. The raw material gas from which sulfur content has been removed in the desulfurization reactor 24 is sent to the reformer 30 together with steam from the steam generator 25 . The reformer 30 is configured as, for example, an externally heated multitubular reactor, and reacts methane gas and steam using, for example, a nickel-based catalyst to generate carbon monoxide and hydrogen. The reformer 30 is supplied with exhaust gas from the air chamber 12 of the fuel cell via a pipe 32, and also with exhaust gas from the fuel chamber 11 of the fuel cell, and in some cases with raw material gas as auxiliary fuel. After being mixed with a portion of the fuel, it is supplied through the pipe 34 and burned in the burner in the reformer 30 .

Now, the raw material gas that has passed through the reformer 30 and been reformed by steam contains carbon monoxide that degrades the electrodes 13 of the fuel cell 10 , so it is sent to the carbon monoxide shift converter 40, where it is oxidized by monoxide. Converts carbon into carbon dioxide.

The hydrogen-containing fuel gas purified in this manner is cooled in a cooler 48 , water is separated in a steam separator 49 , and then supplied to the fuel chamber 11 of the fuel cell 10 via a reservoir tank 50 . The fuel gas is preheated to a predetermined temperature by a suitable method before being supplied to the fuel chamber.

Since the output of the fuel cell 10 is direct current (DC),
The thyristor converter 60 converts it into alternating current (AC) and makes it the final output.

In the figure, the piping system shaded in black is the main route for fuel gas, and the piping system shown in a tubular shape with two lines is the main route for air gas.

Next, before explaining the method for stopping the startup process, an example of a method for discharging or replacing gas in the system at the time of stopping the parts described so far will be described. In the figure, the valves numbered in the 100s are shutoff valves, and the valve symbols are blacked out to make it easier to understand. Valves numbered in the 200s and not shaded out have the following functions:

That is, the odd numbers 201, 203, 2
Valves labeled 05, 207, 209 and 211 are inert gas, such as nitrogen (hereinafter referred to as _N2 ), inlet valves and are marked with inward arrows indicating inlet.

Also, even numbers 200, 202, 20
Valves labeled 4, 206, 208, and 210 are vent valves with outward arrows indicating venting.

Now, with these valves, the piping system of the system is divided into the following six systems in the illustrated embodiment. That is, the first system includes the cutoff valve 101 and the cutoff valve 111.
from the _N2 inlet valve 203 in the auxiliary fuel system between the
N ₂ is introduced and discharged from the vent valve 204. Second
The system is a desulfurization system between the cutoff valve 102 and the cutoff valve 104, in which _N2 is fed through the _N2 feed valve 201 and discharged through the vent valve 202. The third system includes a reformer 30 between the cutoff valve 104 and the cutoff valve 109;
A fuel reforming/transforming system including a carbon monoxide shift converter 40, a steam separator 49, and a reservoir tank 50. Initially, the shutoff valve 105 and vent valve 200 are opened to purge the system with steam, and then the shutoff valve 105 close
_N2 is supplied from the _N2 supply valve 211. N ₂ Inlet valve 2
If step 11 is omitted, open the shutoff valve 104.
_N2 purging and replacement are performed with _N2 from the _N2 inlet valve 201. The fourth system is a system that includes the fuel chamber 11 of the fuel cell between the cutoff valve 108 and the cutoff valve 110, in which _N2 is fed in from the _N2 feed valve 207 and discharged from the vent valve 208. The fifth system is a system that sends the fuel cell fuel exhaust gas between the cutoff valves 109 and 110 and the cutoff valves 111 and 114 to the reformer burner, and feeds _N2 from the _N2 feed valve 205 to the vent valve. 2
Discharge from 06. Finally, the sixth system is a system including the air chamber 12 of the fuel cell between the shutoff valve 115 and the shutoff valve 116, in which _N2 is fed through the _N2 inlet valve 209 and discharged through the vent valve 210.

By dividing the system as described above, in order to reduce thermal shock and protect the catalyst,
The third system can perform steam purge separately from other systems, the first, second, fourth and fifth systems can perform flammable gas purge with N2 between them, and the sixth system can also perform a flammable gas purge with _N2 . By performing _N2 substitution at the same time, effects such as being able to adjust the differential pressure with the fourth system, that is, between both electrodes of the fuel cell and protect the inside of the cell stack, can be obtained.

The inert gas replacement method described above has already been proposed by the present applicant in Japanese Patent Application No. 1987-97121.

Next, the component devices involved in the startup process, which is the object of the present invention, will be explained.

First, for the fuel processing device (consisting of 24, 30, 40, etc.), the starting circulator 70, the piping 8
1 and shutoff valves 301 and 302 are involved. At startup, the inert gas (N ₂ gas) preheated by the startup inert gas preheating means (not shown separately) by the startup circulator 70 is supplied to the desulfurizer 24, reformer 30 , and monoxide by opening the shutoff valves 301 and 302. It is circulated and supplied to the carbon transformer 40 and the like. When the inside of the system is heated to the extent that it can be used for fuel production, the shutoff valve 301,
302 is closed. Thereafter, steam from the steam generator 25 constituting the steam purging means is introduced into the system by opening the shutoff valve 105, and purging is performed by steam. Therefore, before opening the valve 105, there is no air in the fuel processing system.
It is filled with N ₂ gas, and after opening the cut-off valve 105, some or all of the water vapor is supplied. Therefore, the moment immediately before the opening of the bow valve 105 has a meaning as a switching signal.

Next, for the fuel cell device (including 10 , 19, etc.), starting inert gas preheating and starting air heating, which is an oxidant gas heating means, are carried out from the raw material gas source 21 through the shutoff valve 303 and piping 82. vessel 19
The raw material gas is sent to , the burner of the heater 19 is ignited, and the temperature of the air chamber 12 and therefore the entire fuel cell 10 is raised by the heated air by the blower 18 . Since the fuel cell needs to be maintained at an operating temperature of about 200° C., ignition of the burner of the startup air heater 19 is the deciding factor whether the fuel cell is ready to generate power or not. Therefore, this has a meaning as a switching signal.

Thus, the stop mode on the fuel processing device side is divided into two specific stop modes before and after the cutoff valve 105 is opened, that is, with the conditions before and after the start of steam purge as switching conditions.

In the first specific stop mode of the fuel processor, shutoff valves 101, 111, 114, 301, and 3
02 is closed and the starting circulator 70 is stopped. Although only the minimum number of valves and auxiliary equipment are shown in the figure for convenience of explanation, as a general rule, equipment and valves that were operated before the stop signal was detected are reset to the state before activation.

In the second specific stop mode of the fuel processing device, the cutoff valves 101, 111, 114, 102, 104, and 109 are closed, and after the system is purged with water vapor through the cutoff valve 105, the cutoff valve 1 is closed.
05 and vent valves 202, 204 and 20.
6 open _N2 inlet valves 201, 203 and 205
open. Immediately after closing the cutoff valve 105, the vent valve 200 is opened and the _N2 supply valve 211 is opened. After the purge is completed, only the shutoff valve 104 and the N ₂ feed valve 201 are opened to increase the pressure in the system, and then these are closed.

These two specific stop modes are controlled by the shutoff valve 10.
5 is opened as the switching condition, and if the above switching condition is not satisfied when a system stop command is issued, the first specific stop mode is selected, and if it is, the second specific stop mode is selected. Select to stop the device.

Next, the stop mode on the fuel cell device side switches the conditions before and after the burner of the startup air heater 19 is ignited, that is, the conditions before and after the startup inert gas preheating and heating by the oxidizing gas heating means are started. The conditions are classified into two specific stop modes.

In the first specific stop mode of the fuel cell device, the blower 18 is stopped. In this case as well, only the minimum number of valves and auxiliary equipment are shown in the figure for convenience of explanation, but as a general rule, equipment and valves that were operated before the stop signal was detected are reset to the state before activation.

In the second specific stop mode of the fuel cell device, the isolation valves 108, 110, 115, 116, 303 are closed, the blowers 17, 18 are stopped, and then the vent valves 208, 210 and the _N2 inlet valve 2 are closed.
07,209 will be held. Vent valves 208, 210 and _N2 inlet valves 207, 209 after purging
is closed.

These two specific stop modes are selected using the burner ignition confirmation signal of the startup air heater 19 as a switching condition, and when a system stop command (same as that for the fuel processing device) is issued, the above switching conditions are not met. If it is true, the first specific stop mode is selected, and if it is true, the second specific stop mode is selected to stop the device.

Although the two switching conditions described in the above embodiments are the best switching conditions, it may be possible to appropriately select other switching conditions depending on the system.

Therefore, a feature of the present invention is to select two specific stop modes for each of the fuel processing device and the fuel cell device, and to select two specific stop modes for each of the fuel processing devices and fuel cell devices, and to select the specific stop modes for each device based on the switching conditions unique to each device in response to the same system stop command. It consists of selecting a mode and stopping the system.
As a result, if a stop command is issued while the system is full of inert gas, wasteful operations such as purging and reinjecting inert gas and waste of inert gas can be avoided. Since each device can be stopped in the shortest and most effective manner at that time, the time required to stop the system can be shorter than before, and the stop program can also be simplified, reducing overall efficiency and costs. This contributes greatly to the

[Brief explanation of the drawing]

FIG. 1 is a system diagram for explaining an embodiment of the present invention. 10 ...fuel cell, 19...starting air heater, 3
0... Reformer, 40... Carbon monoxide shift converter, 70...
Starting circulation machine, 101-117, 301-303
...Shutoff valve, 201, 203, 205, 207, 2
09,211...N ₂ inlet valve, 200,202,2
04,206,208,210...Vent valve.

Claims (1)

[Claims] 1 A fuel processing device that has an inert gas purge means, a water vapor purge means, and an inert gas preheating means for starting, and generates fuel by reforming and converting raw fuel, an inert gas purge means, and an inert gas preheating means for starting. A method of operating a fuel cell power generation system comprising a fuel cell device having inert gas preheating and oxidizing gas heating means and generating power by receiving the fuel and oxidizing agent, the method comprising: As a shutdown procedure after operation, the fuel processing device performs a steam purge, an inert gas purge, and then performs a predetermined valve operation, and the fuel cell device performs an inert gas purge after stopping oxidizing gas heating, and then performs a predetermined valve operation. As a startup procedure of the system, the fuel processing device performs a steam purge after preheating an inert gas, and the fuel cell device includes a procedure of supplying reformed gas after heating by the heating means. In the method of operating a fuel cell power generation system, the stopping procedure in the startup process of the fuel processing device is switched depending on the conditions before and after the start of the steam purge, the inert gas preheating procedure is stopped before the start of the steam purge, and the inert gas preheating procedure is stopped after the start of the steam purge. Similar to the stop procedure after steady operation, the procedure is to perform a steam purge, an inert gas purge, and then operate a predetermined valve, and the stop procedure in the startup process of the fuel cell device is switched depending on the conditions before and after the start of heating by the heating means. , before the start of heating, a predetermined valve operation is performed, and after the start of heating, the procedure is to perform an inert gas purge after stopping the oxidizing gas heating, and then perform a predetermined valve operation, similar to the stop procedure after steady operation. How to operate a fuel cell power generation system.