JPS61233979A - Controller of fuel cell power generating plant - Google Patents

Abstract

PURPOSE:To keep combustion in a combustion chamber of reformer stable by controlling the flow rate in a fuel electrode by oxygen concentration in exhaust gas from combustion chamber of reformer which is an index of an excess of air. CONSTITUTION:When an oxygen concentration detected value 11 in reformer exhaust gas is reduced below a lower limit value 10, the operation of a reformer temperature controller in conventional control constitution is fixed constant, and a fuel electrode flow rate instruction 9 is reduced with a correction signal 16 to increase oxygen concentration detected value 11. When the oxygen concentration detected value 11 is increased above the lower limit value 10, that is a deviation signal 12 is negative, a temperature deviation correction signal 18 goes 1, and a setting flow rate correction value becomes constant, and it is the same as conventional constitution. When oxygen concentration in exhaust gas from the reformer combustion chamber is extremely reduced, by correcting the fuel electrode flow rate instruction 9 downward, extreme decrease in air excess and incomplete combustion are prevented.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a control device for a fuel cell power plant, and particularly to a control device for a fuel cell power plant that maintains a stable combustion state in a reformer combustion chamber. .

[Technical background of the invention and its problems] A fuel cell power generation plant generates hydrogen gas from raw material gas through a reformer, supplies this hydrogen gas to the cell body, causes an electrode reaction to occur, and then reforms the fuel cell again. It has a series of configurations in which the reformer is recovered and used as fuel for the reformer combustion chamber.

The reformer combustion chamber is provided to supply the thermal energy necessary to generate hydrogen gas from the raw material gas, and the combustion chamber burner is supplied with combustion air and combustion fuel to supply thermal energy. control the amount of supply. An example of a conventional configuration for controlling the amount of thermal energy supplied will be described below.

FIG. 3 is a block diagram of a conventional fuel electrode flow control configuration, and will be explained using this diagram. In Figure 3, 1 is the load (or battery current value), 2 is the flow rate setting function, 3 is the flow rate command value based on the load, and 4 is the representative temperature of the upper part of the reformer reaction chamber or the upper part of the metal outside the reaction chamber. Setting value for 5
6 is a detected value of the representative temperature, 6 is a deviation signal between both temperatures, and 7 is a regulator that provides a set flow rate correction 1ia8 to the flow rate command value based on the deviation signal 6.

In this example, a set flow rate correction value 8 is added to the flow rate command value 3 corresponding to the load 1 so that the reformer representative temperature detected value 5 becomes the reformer representative temperature set value 4, and the final fuel electrode This configuration provides a flow rate command value of 9.

When the fuel electrode flow rate command value 9 is given, the regulator 32 issues an opening command 33 to the fuel electrode flow rate control valve 34 based on the flow rate deviation 31 between the fuel electrode flow rate command value 9 and the fuel electrode flow rate detection value 3G. Control is achieved by giving

[Problems with Background Art] In the conventional device having the above configuration, for example, when the detected reformer representative temperature value 5 decreases, the fuel electrode flow rate command value 9 increases by the set flow rate correction value (correction command) 8. That is,
In order to increase the reformer representative temperature detection value 5, the fuel electrode flow rate is increased, that is, the fuel flow rate in the reformer combustion chamber is increased. However, in this case, the air excess ratio of the reformer combustion chamber burner, which is determined by the flow rate of combustion air into the reformer combustion chamber, decreases, which sometimes leads to incomplete combustion in the reformer combustion chamber. .

[Object of the Invention] The present invention has been made to solve the above problems, and provides a control device for a fuel cell power plant that can avoid an extremely low excess air ratio and incomplete combustion in a reformer. is intended to provide.

[Summary of the Invention] In the present invention, in the control device for the fuel cell power generation plant described in the conventional example, there is provided a means for detecting the oxygen concentration in the combustion exhaust gas from the combustion chamber of the reformer, and a means for detecting the oxygen concentration in the combustion exhaust gas from the combustion chamber of the reformer. The present invention is characterized in that a control means for changing the extreme flow rate command value 9 is provided.

[Embodiments of the Invention] Examples will be described below with reference to the drawings. FIG. 1 shows an embodiment of the present invention. 1 to 9.30 in the diagram
34 corresponds to FIG. 10 is the lower limit set value of the reformer combustion chamber exhaust gas oxygen concentration, 11 is the detected oxygen concentration value, 1
2 is the oxygen concentration deviation. The oxygen concentration deviation 12 provides a signal 18, in part by the function generator 11, to the representative temperature control section of the reformer. The signal 18 becomes 1 when 12 is a positive value, that is, when the detected oxygen concentration value 11 is less than or equal to the lower limit setting value 10 and when O1 is a negative value. Further, the oxygen concentration deviation 12 becomes a correction signal 14 by the function generator 13, which is further outputted to the regulator 1.
5 gives a set flow mountain correction value (correction command) 16 for the fuel electrode flow rate command value 9 in the conventional example. The function generator 13 is a function that sets the correction signal 14 to 0 when the deviation signal 12 is negative, and sets the signal 12 as the signal 14 when it is positive. That is, this embodiment is configured to switch from the conventional reformer representative temperature control to reformer exhaust gas oxygen concentration control when the reformer exhaust gas oxygen concentration becomes equal to or less than its lower limit.

Next, the operation of this embodiment will be explained. When the detected value 11 of the reformer exhaust gas oxygen concentration decreases transiently and becomes equal to or less than the lower limit set value 10, the deviation signal 12 becomes a positive value.

Since the deviation signal 12 is a positive value, the function generator 11 generates a signal 1.
Outputs 8 and 0. When the signal 18 is O, the temperature deviation 6 of the reformer is multiplied by a multiplier 19 to 0, and this is input to the regulator 7 as a corrected temperature deviation signal 20. That is, when the detected oxygen concentration value 11 becomes equal to or lower than the lower limit set value 10, the set flow rate correction value 8 based on the temperature deviation of the reformer is held constant.

Similarly, when the deviation signal 12 becomes a positive value, the function generator 13 inputs the deviation signal 12 as it is as a correction signal 14 to the regulator 15, and the regulator 15 further inputs the deviation signal 12 as a correction signal 14 to the regulator 15. A reduction command 16 is output.

As a result, it acts to reduce the fuel electrode flow rate command value 21 according to this embodiment.

In short, in this embodiment, when the detected value 11 of the reformer exhaust gas oxygen concentration becomes equal to or lower than the lower limit set value 10, the operation of the reformer temperature control section in the conventional control configuration is fixed to a constant value,
In order to increase the detected oxygen concentration value 11, the correction signal 16 acts to decrease the fuel electrode flow rate command value 9.

Note that when the oxygen concentration detection value 11 is larger than the lower limit setting value 10, that is, when the deviation signal 12 is a negative value, the temperature deviation correction signal 18 becomes 1 and the set flow mountain correction value 16 becomes constant. It provides the same effect as the conventional configuration.

The above-mentioned action accompanying this embodiment is such that when the oxygen concentration in the exhaust gas from the reformer combustion chamber is extremely reduced, the I-material polar flow mother command value 9 is corrected in a downward direction. In other words, the effect of preventing the excessive air ratio in the combustion chamber from being excessively reduced and incomplete combustion is brought about.

FIG. 2 is a configuration diagram showing another embodiment of the present invention. 1-16, 20, 21, 30-34 in the figure correspond to FIG. A function generator 22 generates 0'.□ when the deviation signal 12 has a positive value, and generates a positive value with a relatively large absolute value when the deviation signal 12 has a negative value as the temperature deviation correction signal 23. 24 is a low value priority circuit for the deviation signal 6 and the correction signal 23.

In this embodiment, when the detected oxygen concentration value 11 becomes below the lower limit set value 10 and the deviation signal 12 becomes a positive value, the correction signal 2
3 becomes O, and the upper limit of the input 20 to the regulator 7 is set to O1 by the low value priority circuit 24, ie the effect of cutting off only the increasing effect of the signal 8. The reduction operation of the signal 8 that occurs when the reformer representative temperature detection value 5 rises transiently operates in the same manner as in the conventional example.

Furthermore, when the deviation signal 12 has a negative value, the correction signal 23 has a large positive value, so the signal @20 output from the low value priority circuit 24 is the same as the temperature deviation 6, which is also the same as the conventional example. It has a similar effect. Note that the effect of the deviation signal 12 on the set drift mountain correction value 16 is the same as in the embodiment described above.

As with the previous embodiments, this embodiment also brings about the effect of extremely reducing the excess air ratio in the combustion chamber of the reformer and preventing incomplete combustion. However, the detected oxygen concentration value 11 is the lower limit set value 101! In the above-mentioned embodiment, the operation of the typical temperature control section of the reformer is held when the
In this example, the set flow rate correction value (correction command) of the temperature control section
Only the increase operation of 8 is restricted, but the decrease operation is performed.

[Effects of the Invention] As explained above, according to the present invention, when the load changes, especially when the typical temperature of the reformer decreases, the excess air ratio in the reformer combustion chamber decreases significantly and incomplete combustion occurs. The fuel electrode flow layer is controlled by the oxygen concentration in the reformer combustion chamber exhaust gas, which is an indicator of excess air ratio, which solves the problem and improves reforming efficiency. It becomes possible to maintain a more stable combustion state in the combustion chamber of the device.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the control device for a fuel cell power plant according to the present invention, FIG. 2 is a block diagram of another embodiment of the control device for a fuel cell power plant according to the present invention, and FIG. 3 is a block diagram of a conventional control device for a fuel cell power plant. FIG. 1 is a configuration diagram of a control device for a fuel cell power generation plant. 1...Load 2...Flow [I setting function 3
...Flow rate command value 4...Reformer representative temperature setting value 5...Reformer representative temperature detection value 6.20...Temperature deviation signal 7.15.32...Adjuster 8.16 ... Set flow rate correction value 9.21 ... Fuel electrode flow rate command value 10 ... Lower limit set value 11 ... Oxygen concentration detection value 12.14 ... Oxygen concentration deviation (after correction) 13.11
．． 22... Function generator 18. 23... Temperature deviation correction signal 19... Multiplication calculator 24... Low value priority circuit 30... Fuel electrode flow m detection value 31... Flow rate deviation 33
...Opening command 34...Fuel electrode flow rate control valve (7317) Agent Patent attorney Norichika Kensuke (and 1 other person) Demon 1 ward 2 diagram 11 elements! ! Einuri soil price

Claims (1)

[Claims] In a control device for a fuel cell power plant that controls the flow rate of reformed gas from a reformer by giving a flow rate command value such that the representative temperature of the reformer becomes a set value, A control device for a fuel cell power generation plant, characterized in that the control device detects an oxygen concentration and adds a flow rate command value based on the detected oxygen concentration value to a flow rate command value based on the reformer representative temperature.