Chemical apparatus and process disinfecting – deodorizing – preser – Control element responsive to a sensed operating condition – Control element responds proportionally to a variable signal...
Reexamination Certificate
1999-07-12
2003-10-07
Johnson, Jerry D. (Department: 1764)
Chemical apparatus and process disinfecting, deodorizing, preser
Control element responsive to a sensed operating condition
Control element responds proportionally to a variable signal...
C422S105000, C422S107000, C422S108000, C422S110000, C422S112000, C422S116000
Reexamination Certificate
active
06630109
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to a reformer for reforming reformate fuel into a desired fuel such as hydrogen-rich gas, and more particularly to an apparatus for controlling the temperature of such reformate fuel. This invention also relates to a method of controlling a reformer using the apparatus.
2. Description of Related Art
A reformer for generating gas mainly composed of hydrogen gas by using methyl alcohol (methanol) and water as reformate fuel materials is known. In this reformer, a copper alloy or the like is used as catalyst, and the active temperature of the catalyst is, for example, 280° C., and when the temperature is lower than the activation temperature, the methanol is not reformed sufficiently, and the amount of residual methanol in the reformate gas increases. Moreover, because the reforming reaction of methanol is an endothermic reaction, heat is supplied from an external source in order to promote the reforming reaction as well as to maintain the catalyst temperature.
The heating method includes, aside from heating by a burner, a method of generating heat by an oxidation reaction and transferring the heat to the reforming portion. The latter method is a so-called partial oxidation reaction method, in which, for example, air is mixed in methanol vapor, and it is oxidized in the presence of catalyst to generate hydrogen, and the heat generated at this time is utilized. Therefore, by utilizing this partial oxidation reaction, the heat accompanying reforming reaction is replenished by the partial oxidation reaction, and the heat absorption and heat generation are balanced, so that heating from an external source is not necessary. In this method, however, only the thermal balance is achieved in the reforming portion so as not to cause temperature changes due to reforming or oxidation, and it is not intended to be applied to setting of the reforming portion to a desired temperature.
That is, to set the temperature of the reforming portion to an appropriate temperature for the reforming reaction or catalyst activity, heating from an external source is required. Accordingly, in this kind of reformer, by the heat generated in the combustion portion, steam of a specified temperature is obtained from a mixture of methanol and water, and the steam is supplied into the reforming portion.
When this reformer is used, for example, to generate fuel gas in a fuel cell, it is necessary to control the reaction in the reformer depending on variation of load of the fuel cell. That is, along with an increase of load, the production of reformate gas must be increased. When the load drops, the production of reformate gas must be decreased. To increase or decrease the generation of reformate gas, it is required to increase or decrease the material to be supplied to the reforming portion, that is, the mixed steam of methanol and water, but for this purpose it is necessary to increase or decrease the heating calorific value for generating the mixed steam of methanol and water at a desired temperature.
The amount of heat required to generate a mixed steam of methanol and water can be controlled by increasing or decreasing the amount of fuel for heating such as methanol. However, the burner or heat generating device using an oxidation catalyst conventionally used as a heating device for heating the mixture of methanol and water is low in the response of heat generation, and it is hence difficult to control heating promptly coping with load fluctuations in such known reformers. That is, in the event of a sudden load increase, the heat generation is insufficient for the amount of methanol and water to be heated, and the steam temperature or catalyst temperature drops. Consequently, the reforming reaction becomes dull, or the residual methanol amount in the reformate gas increases, and the performance of the fuel cell declines. To the contrary, if the load drops suddenly, due to delay in drop of heating amount, the steam temperature or catalyst temperature may elevate excessively, and the activity of the catalyst is lowered.
To eliminate such disadvantage, the invention disclosed in Japanese Patent Publication No. HEI 7-105240 is intended to control the temperature depending on load fluctuations by controlling the steam ratio. That is, by decreasing the amount of water mixed as reformate fuel, the amount of heat required for heating and evaporation drops, and the temperature of the mixed steam of methanol and water as reformate fuel rises. However, when the amount of water is increased, the amount of heat required for raising the temperature and evaporating increases, so that the temperature of the mixed steam of methanol and water as reformate fuel declines.
The method of temperature control disclosed in this publication comprises changing the amount of water, changing the amount of heat consumed or absorbed by the water, and thereby controlling the temperature. Therefore, as compared with the method of controlling the heat generation amount by changing the amount of fuel for combustion, the response of temperature control is improved. This published method, however, consumes part of the heat generated for heating and evaporation on the condition that the heat generation by combustion of the fuel is constant. For example, in the case of lowering the reformate gas amount due to small fluctuations in the fuel cell, the amount of heat generation by combustion is maintained higher than the amount of heat determined theoretically. As a result, the combustion is controlled to generate more heat than the heat actually required for reforming the reformate fuel, and the fuel is consumed more than necessary, and thus the fuel economy drops. Also in this published invention, spent fuel containing residual hydrogen is used as a part of the fuel for heating the reformate fuel, and the reformate fuel is heated by burning the residual hydrogen by a burner. Yet, if the reformate fuel is heated by burning the residual hydrogen by a burner, the amount of heat is not controlled. Thus, because the temperature is controlled by the steam ratio, the consumption of the heating fuel containing residual hydrogen that is required is more than the amount needed for heating of reformate fuel. In this respect, also, the residual hydrogen is consumed excessively, and thus this known method has been susceptible to improvement in a more effective use of fuel.
SUMMARY OF THE INVENTION
The invention has been made in the light of the above-described background. It is an object of the present invention to provide a control apparatus that can control combustion fuel for heating reformate fuel, control the reformate fuel temperature to a desired temperature suitable for the reforming reaction, and utilize the reformate fuel effectively.
To achieve this object, the invention uses unreacted flammable gas in the emission resulting from energy conversion of reformate gas for heating of reformate fuel, and controls the amount of unreacted flammable gas for combustion for heating at an appropriate amount depending on the required amount of reformate fuel, as well as on other factors.
In a first aspect of the invention, a control apparatus is provided for controlling a reformer. The reformer can comprise a reformate gas generator that gasifies a reformate fuel by a reforming reaction, the combustion portion that heats the reformate fuel by burning the emission including unreacted flammable gas generated at the time of conversion of the reformats gas obtained from the reformate gas generator into another energy form by an energy converter. The control apparatus comprises a reformed amount assessing device that assesses the amount of reformate fuel to be gasified, and an emission amount assessing device that assesses the amount of emission to be supplied into a combustion portion on the basis of the assessed reformate fuel amount.
Therefore, according to the invention, when the amount of the reformate fuel varies depending on fluctuations of load in the energy converter or the like, th
Maeda Iwao
Motozono Yoshikazu
Nagamiya Kiyomi
Taki Masayoshi
Yamaoka Masaaki
Johnson Jerry D.
Oliff & Berridg,e PLC
Ridley Basia
Toyota Jidosha & Kabushiki Kaisha
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