JPH0755801B2 - Fuel reforming system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to a fuel reforming system, and in particular, is improved so that the flow rate of combustion air can be appropriately controlled. The present invention relates to a fuel reforming system.

(Prior Art) In order to use a raw material gas such as hydrocarbon or methanol as a fuel for a fuel cell, it is necessary to reform these into a hydrogen-rich gas and send them into the fuel cell. It is used.

A general configuration of such a fuel reforming system is shown in FIG. That is, in FIG. 2, inside the fuel reforming apparatus 1, a reforming pipe 2 for reforming into hydrogen-rich gas by bringing a mixed gas of raw fuel and steam into contact with a catalyst, and exhaust gas from the fuel cell are provided. A combustor 3 and a combustion chamber 4 that burn are provided. In addition, a reaction gas obtained by mixing a raw fuel such as natural gas and steam for reforming is introduced into the reforming pipe 2 through a raw fuel regulating valve 5 and a steam regulating valve 6, respectively. ing. This reaction gas is heated in the reforming pipe 2 by the combustion gas combusted in the combustor 3 provided in the combustion chamber 4, and is reformed into the reformed gas containing hydrogen as a main component, and then the reformed gas is Carbon oxide transformer 7
Through which the reaction product, carbon monoxide, is converted into carbon dioxide, which is harmless to the fuel cell. Then, in the reformed gas, excess steam introduced for the reforming reaction is removed by condensation in the condenser 8, and the fuel control valve 9
Is supplied to the fuel cell via. The reformed gas introduced into the fuel cell consumes hydrogen by an electrochemical reaction here, is exhausted, is then introduced into the combustor 3 of the fuel reformer 1, and is supplied through the air regulating valve 10. And is used as a heat source for the reforming. Further, on the combustion exhaust gas line drawn out from the fuel reformer 1, an oxygen concentration measuring device 11 for measuring the oxygen concentration contained in the exhaust gas is provided, and the measurement result by this measuring device is used as a measurement signal. The target value of the flow rate of the combustion air supplied to the combustor 3 is set on the basis of the measurement signal sent to the control device 12, and the air control valve 10 is set in accordance with the value. A valve opening signal for controlling the opening of the air control valve 10 is sent to the air control valve 10.

The method of measuring the oxygen concentration in such combustion exhaust gas and adjusting the flow rate of combustion air according to the measured value is
In the fuel reformer for a fuel cell, which is proposed in JP-A-62-97268 and characterized in that the load fluctuation is large, a decrease in the excess air ratio in the combustion chamber during a transient load change or the like,
There is an advantage that incomplete combustion can be avoided and the supply amount of combustion air can be constantly saved.

(Problems to be Solved by the Invention) However, the conventional fuel reforming system configured as described above has the following problems to be solved.

That is, in general, the fuel reforming apparatus 1 is often provided with a monitoring window on the container for the purpose of externally observing, monitoring or television monitoring the combustion state and flame state inside the fuel reforming apparatus 1.
In addition, in order to measure the temperature of the reforming tube 2 from the outside, it is also monitored by an infrared sensor through a sensor window provided in the container. In such a monitoring window and sensor window 13,
Heat-resistant glass is used, but a method of injecting cooling air 14 for cooling the window is used so that the hot combustion gas does not directly contact the inside of the glass window.

However, when the number of monitoring windows and sensor windows 13 provided in the container is large and the injection amount of the cooling air 14 is also large, the oxygen concentration contained in the combustion exhaust gas does not reflect the excess air ratio in the combustor 3, In particular, there is a problem that the air supply amount in the combustion chamber is reduced in a transient state due to load fluctuation. That is, the oxygen concentration contained in the combustion exhaust gas also includes oxygen in the air supplied for window cooling, and it is determined that the excess air ratio in the combustion exhaust gas is large, and the air control valve 10 is opened. Due to the limited degree, the amount of air supplied will be reduced.

The present invention has been proposed in order to solve the above drawbacks, and an object thereof is to accurately measure the oxygen concentration in the gas in the combustion chamber and the excess air ratio, and appropriately adjust the supply flow rate of the combustion air. It is to provide a fuel reforming system that can do the above.

[Structure of the Invention] (Means for Solving the Problem) The present invention introduces a reaction gas obtained by mixing a raw fuel and water vapor into a reforming tube, and at the same time, supplies a fuel and combustion air to a combustor. A fuel reforming device for reforming the reaction gas into reformed gas by passing combustion gas obtained by supplying and burning the reformed gas through an outer surface of the reforming pipe, wherein a monitoring window or a sensor is provided in the container. A fuel reforming device provided with windows and configured to inject cooling air into the container to cool the windows, and the oxygen concentration in the combustion gas is measured, and the concentration thereof is measured. A control system configured to adjust the flow rate of the combustion air according to the above, in the combustion gas flow path from the combustor to the outer surface of the reforming pipe, the monitoring window or the sensor window. Gas sump above the installation location Disposed a ring member, by connecting the gas sampling member to the oxygen concentration measuring device, is characterized in that to measure the oxygen concentration in the combustion gas in an intermediate position of the combustion gas flow passage.

(Operation) According to the fuel reforming system of the present invention, the oxygen concentration in the combustion gas immediately after coming out of the combustor is measured, so that it is possible to accurately measure the oxygen concentration without being affected by the window cooling air. Therefore, it is possible to always supply an appropriate amount of air into the combustor.

(Example) Hereinafter, one example of the present invention will be specifically described with reference to FIG. The same members as those of the conventional type shown in FIG. 2 are designated by the same reference numerals and the description thereof will be omitted.

In the present embodiment, as shown in FIG. 1, a gas sampling member 21 for sampling the gas in the combustion gas is connected to the oxygen concentration measuring device 20, and this gas sampling member 21 is connected to the combustor 3 Is provided above the location where the monitoring window or sensor window 13 is provided in the combustion gas flow path from the outside to the outer surface of the reforming pipe 2. Then, the oxygen concentration in the combustion gas at the intermediate position of the combustion gas passage can be measured.

The sampling by the gas sampling member 21 is configured to be performed at a site where the air for cooling the window is not mixed.

In the fuel reforming system of this embodiment having such a configuration, since the oxygen concentration in the combustion gas from the combustor 3 to the reforming pipe 2 is measured, the monitoring window and the sensor window 13 provided in the container 13 The cooling air 14 delivered to the does not affect the measurement, and it is always possible to accurately measure the excess air ratio in the combustor. Therefore, based on the value of the oxygen concentration in the combustion gas measured by the oxygen concentration measuring device 20 according to the present embodiment, by setting the flow rate target value of the combustion air, by adjusting the opening of the air control valve 10. , Can always supply the right amount of air.

[Effects of the Invention] As described above, according to the present invention, the gas sampling member is provided in the combustion gas passage extending from the combustor to the outer surface of the reforming pipe, above the location where the monitoring window or the sensor window is provided. However, by connecting this gas sampling member to an oxygen concentration measuring device, the oxygen concentration in the combustion gas at the intermediate position of the combustion gas flow path is configured to be measured. It is possible to provide a fuel reforming system capable of accurately measuring the air excess ratio and appropriately adjusting the supply flow rate of combustion air.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the fuel reforming system of the present invention, and FIG. 2 is a block diagram showing an example of a conventional fuel reforming system. 1 ... Fuel reforming device, 2 ... Reforming tube, 3 ... Combustor, 4
…… Fuel chamber, 5 …… Raw fuel control valve, 6 …… Steam control valve, 7 …… Carbon monoxide transformer, 8 …… Condenser, 9 …… Fuel control valve, 10 …… Air control valve, 11 ...... Oxygen concentration measuring instrument,
12 ... Control device, 13 ... Monitoring window or sensor window, 14 ...
… Window cooling air, 20… Oxygen concentration measuring instrument, 21… Gas sampling member.

Claims (1)

[Claims] 1. A reaction gas obtained by mixing raw fuel and water vapor,
The reaction gas is reformed by introducing the combustion gas into the reforming tube and supplying the fuel and the combustion air to the combustor for combustion to pass the combustion gas through the outer surface of the reforming tube. A fuel reforming device for reforming into gas, wherein the container is provided with a monitoring window or a sensor window, and cooling air is injected into the container to cool these windows. And a control system configured to measure the oxygen concentration in the combustion gas and adjust the flow rate of the combustion air according to the concentration. Of the combustion gas flow path from the reactor to the outer surface of the reforming pipe, a gas sampling member is arranged above the installation location of the monitoring window or the sensor window, and the gas sampling member is connected to an oxygen concentration measuring device. Burning moth The fuel reforming system which is characterized by measuring the oxygen concentration in the combustion gas in an intermediate position of the flow channel.