Furnaces – Process – Incinerating refuse
Patent
1991-11-25
1993-07-13
Yuen, Henry C.
Furnaces
Process
Incinerating refuse
110245, 110101CF, F23G 300, F23G 500
Patent
active
052263746
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method of controlling combustion of a fluidized-bed incinerator.
BACKGROUND ART
As shown in FIG. 9, in a fluidized-bed incinerator 5, fluidized sand of a fluidized bed 6 constituted by the fluidized sand circularly supplied to the lower portion of the incinerator is preheated to a temperature of about 100.degree. C., and fluidizing air 16 allows the sand to flow. In this state, combustion materials supplied from a charge shoot 2 are combusted for a short time. An unburnt gas on the fluidized bed 6 is combusted by secondary air 15 supplied to a free board portion 13, and a combustion exhaust gas 14 is exhausted from a top portion of the incinerator 5.
Incombustibles contained in the combustion materials are exhausted from the bottom portion of the incinerator together with the fluidized sand. The fluidized sand is separated from the incombustibles and recycled in the incinerator.
In order to control a combustion state of the fluidized-bed incinerator, as is disclosed in Published Unexamined Japanese Patent Application No. 53-14865, the following method is employed. That is, an oxygen concentration in exhaust gas is detected to control a supply rate of combustion materials such as garbage.
A combustion state in an incinerator is determined by brightness or the like in the incinerator. For example, when the combustion becomes strong, a fluidizing air flow rate is decreased to cause the combustion to be weak. This method is disclosed in PCT WO88/8504.
PROBLEM TO BE SOLVED BY THE INVENTION
For example, when a large amount of waste is charged into an incinerator from a charge shoot at one time, since a combusting operation is performed for a short time, e.g., several seconds, a large amount of unburnt gas may be generated for a lack of combustion air. The large amount of unburnt gas is exhausted out of the incinerator without being completely combusted even on a free board portion. The exhaust gas has a low oxygen concentration and contains harmful gases such as CO gas, thereby causing environmental pollution.
In this case, even when the operation of the incinerator is controlled by measuring the oxygen concentration of the exhaust gas, an oxygen concentration meter available at present measures an oxygen concentration to have a time lag of several ten seconds. Therefore, the meter cannot respond to a change in combustion state within a short period of time.
When a combustion state in an incinerator is determined by brightness in the incinerator, a time lag is smaller than that caused when the combustion state is controlled by measuring an oxygen concentration. However, since the combustion state is determined after combustion materials are combusted, the incineration cannot always be stably controlled.
It is an object of the present invention to provide a method of controlling combustion of a fluidized-bed incinerator so as to solve the above problem.
DISCLOSURE OF INVENTION
According to the present invention, in a fluidized-bed incinerator, a method of controlling combustion of a fluidized-bed incinerator comprises measuring a waste supply rate by a supply rate measuring unit using a photoelectric element arranged on a shoot for supplying incineration waste from a dust feeder to the incinerator, and when the incineration waste supply rate is higher than a predetermined value,
decreasing the supply rate of the incineration waste of the dust feeder to suppress a combusting operation.
An induced gas flow rate of an exhaust gas induced blower of the incinerator is increased to limit an increase in incinerator internal pressure.
An air flow rate of fluidizing air of a forcing blower is decreased to suppress a combustion operation.
An air flow rate of a blower for supplying air to a free board portion is increased to prevent production of unburnt gases.
A flow rate of the fluidizing air is instantaneously decreased, and at the same time, air is supplied to the free board portion at a flow rate corresponding to the decrease, thereby suppressing a combusting
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Kawakami Masaaki
Noto Takashi
Suzuki Yasuo
Tsuboi Haruhito
Yamagishi Miki
NKK Corporation
Yuen Henry C.
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