Power plants – Motive fluid energized by externally applied heat – Process of power production or system operation
Reexamination Certificate
2001-02-13
2002-09-03
Nguyen, Hoang (Department: 3748)
Power plants
Motive fluid energized by externally applied heat
Process of power production or system operation
C060S676000
Reexamination Certificate
active
06442938
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a fuel reformer and a waste processing system including a fuel reformer, and especially to a direct heat exchange type, non catalyst fuel reformer, and a waste-to-energy incineration system in which a direct heat exchange type, non catalyst fuel reformer is adopted.
2. Description of Related Art
As a fuel reformer for reforming source fuel such as hydrocarbon material to a gas containing hydrogen, an indirect heat exchange type fuel reformer or a direct heat exchange type reformer has been largely used. Further, there are two types of fuel reformers, that is, a fuel reformer using a catalyst and a fuel reformer which does not use a catalyst.
In an indirect heat exchange type fuel reformer, a reaction tube and a burner are provided. While the reaction tube is heated by the combustion gas from the burner, raw gas enters the reaction tube at an end of the reaction tube. Further, the raw gas is partially oxidized (so-called partial combustion), and reformed to gas including hydrogen, either by using a catalyst or by using coolant steam on a basis of hydrothermal reaction.
On the other hand, in an direct heat exchange type fuel reformer, the heat required for reforming raw fuel is directly given to raw fuel flowing in a fuel flowing path by partial oxidization, which results in a high temperature gas of raw fuel. The high temperature raw fuel (hereafter, referred to as fuel for simplicity) is reformed to gas including hydrogen, either by using a catalyst or by using a steam coolant on a basis of hydrothermal reaction. In a chemical industrial plant, a direct heat exchange type reformer is mainly used.
In the method of using a catalyst, since the catalyst can lower the reforming energy, that is, the reforming temperature to about 700° C., only 20% of the fuel is consumed for partial oxidization.
In the method of using no catalyst, due to the absence of a catalytic energy saving effect, more than 20% of the fuel is required for partial oxidization in order to obtain a reforming energy, that is, the reforming temperature as high as 1300° C.
One of features of the waste-to-energy incineration system is that the generated heat changes due to changes of the amount of waste to be processed, depending on the day, the season or the year, which is particular to the waste processing. Further, since the waste processing is requested to be performed without stopping of operations, in addition to the above-mentioned feature, a maintenance-free composition or structure is strongly required for the waste-to-energy incineration system. For satisfying the above-mentioned requirement, each apparatus composing the system should be composed of long-service parts. To realize the above-mentioned apparatus, the method in which a catalyst is not used, is advantageous. However, in this method, it is indispensable to produce energy necessary for reforming fuel gas by partially oxidizing more than 20% of fuel in order to reform fuel gas with the partial oxidation heat itself of fuel gas. (Hereafter, a fuel reformer mainly indicates a fuel reformer without a catalyst, in which more than 20% of fuel is partially oxidized.)
An existing fuel reformer has been usually used, for example, in a gas turbine power generation system. Further, a power generation system in which a fuel reformer is provided, is disclosed in JP-A-286835/1990, JP-A-332166/1993 and JP-A-332167/1993.
Since the previously-mentioned indirect heat exchange type fuel reformer includes a burner for heating a reaction tube, such a fuel reformer has a problem in that the size of the apparatus becomes large, and an external heat source has to be provided.
On the other hand, a direct heat exchange type fuel reformer is superior to an indirect heat exchange type fuel reformer in the point that the fuel itself produces a heat source for reforming fuel gas by partially oxidizing the fuel. In addition, due to the absence of a burner and a reaction tube, the size of the fuel reformer can be reduced in comparison with the indirect heat exchange type.
One of the objects of the waste-to-energy incineration system is to burn waste and decrease the volume of waste, without polluting the environment. Another objects is to generate power by utilizing the heat generated in burning waste. Therefore, it is very important to remove hazardous material from exhaust gas generated in an incinerator. In particular, removal of dioxin has been a very pressing subject.
The apparatuses disclosed in JP-A-286835/1990, JP-A-332166/1993 and JP-A-332167/1993 are mainly used for a gas turbine power generation System. The above-mentioned subject is out of the question with these devices because of using fuel different from the waste. Therefore, the conventional reformer are not based on the same subject. Further, since various kinds of waste are burned in an incinerator, the amount of generated heat changes hour by hour, month by month and year by year. Consequently, since the amount of fuel fed to a fuel reformer changes, corresponding to the amount and the components of gas exhausted from the incinerator, an existing direct heat exchange type fuel reformer a problem, that a fire-proofing brick structure part inside the incinerator is easily damaged and worn out due to the changes in the generated heat.
SUMMARY OF THE INVENTION
Objectives of the Invention:
The present invention is intended to solve the above-mentioned problems, and the objectives of the present invention are as follows.
A first objective of the present invention is to provide a waste-to-energy incineration system which is able to stably decompose generated dioxin, in which the composition and the heat value of exhaust gas fluctuates over time, and which utilizes reformer.
A second objective of the present invention is to provide a waste-to-energy incineration system and a fuel reformer which are able to stably decompose generated dioxin and to suppress NOx generation.
A third objective of the present invention is to provide a waste-to-energy incineration system having a highly reliable performance with respect to dioxin decomposition and a highly efficient waste-to-energy incineration performance.
Method of Solving the Problem:
To attain the above-mentioned first and third objectives, the present invention provides a waste-to-energy incineration system, comprising:
an incinerator for burning waste;
a boiler in the incinerator for generating steam by using exhaust heat generated by the incinerator;
a superheater for superheating steam generated in the boiler;
a steam turbine driven by steam superheated by the superheater;
a generator driven by the steam turbine;
a fuel reformer for reforming fuel; and
a combustor burning fuel gas which is reformed by the fuel reformer, and at least a part of an incinerator exhaust gas.
Further, in a waste-to-energy incineration system, the system comprises:
an incinerator for burning waste;
a boiler in the incinerator for generating steam with exhaust heat generated in the incinerator;
a steam utilizer for utilizing steam generated in the boiler; and
a fuel reformer for reforming fuel;
wherein fuel gas reformed by said fuel reformer is led to said incinerator.
Further, in a waste-to-energy incineration system, the system comprises:
an incinerator for burning waste;
a first boiler in the incinerator for generating steam with exhaust heat generated in the incinerator;
a steam utilizer for utilizing steam generated in the boiler;
a second boiler different from the first boiler;
a fuel and reformer for reforming fuel;
a combustor for burning fuel gas which is reformed by the reformer, and at least a part of an incinerator exhaust gas;
wherein steam generated by the second boiler is led to the fuel reformer.
To attain the above-mentioned second objective, the present invention provides a waste-to-energy incineration system, comprising:
an incinerator for burning waste;
a boiler in the incinerator for generating steam by using exhaust heat generated in the incinerator;
a superheater for reheating steam
Ajiro Taiko
Hatamiya Shigeo
Ishigaki Yukio
Koyama Kazuhito
Okusawa Tsutomu
Hitachi , Ltd.
Mattingly Stanger & Malur, P.C.
Nguyen Hoang
LandOfFree
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