Ishikawajima-harima Heavy Industries Co., Ltd.

Satoshi Inoue

Minoru Narisoko

Hitoshi Hagihara

Takehiko Motomura

Mikio Kiyotomo

Minoru Fukusaki

The ash melting furnace disposes the combustion ash resulted from incineration of municipal or other sorts of waste by melting it utilizing as the main fuel the unburnt carbon contained in the ash itself. The ash melting furnace includes a stationary plasma torch which uses air for the working gas, and which is so placed facing the combustion ash heaped up within the furnace as to project its hot gas jet thereon. The furnace further includes a torch unit controller that actuates the plasma torch to secondarily heat and melt the ash.

Ash melting furnace

Waste is combusted by an incinerator and becomes an ash. The ash is transferred to a melting furnace to be melt therein. The ash contains unburned carbon and the melting at the melting furnace is influenced by an amount of the unburned carbon. The amount of unburned carbon largely depends on a gas temperature at an waste inlet of the incinerator and an waste burn-out point in the incinerator. The waste disposal method, using the incinerator and the melting furnace, comprises the steps of detecting the gas temperature at the waste inlet of the incinerator, detecting the burn-out point of waste combustion in the incinerator, controlling a waste transfer speed in the incinerator and controlling a flow rate of air fed into the incinerator such that the detected temperature and burn-out point remain within repsective predetermined ranges, which in turn brings the amount of the unburned carbon remaining in the ash to a desired value, whereby the melting at the melting furnace is controlled to a desired melting.

Waste disposal method and apparatus

A hearth arrangement for a furnace which melts refuses carried on the hearth arrangement comprises a plurality of hearth blocks arranged like a stair. The heart blocks are inclined stepwise in a refuse carrying direction and each hearth block has a width direction perpendicular to the refuse carrying direction. Each hearth block is divided into two block elements in the width direction of the hearth block and the two block elements are joined to each other by springs which exerts a biasing force on the block elements in the width direction of the hearth block. A clearance is formed between each two adjacent hearth blocks to tolerate heat expansion of the hearth blocks. Each block has a protuberance extending over a next hearth block located in the ash carrying direction such that the ash does not flow into the clearance between the hearth blocks. A convex portion is formed on a contacting plane of one block element and a concave portion is formed in a contacting plane of the other block element such that the convex portion engages with the concave portion to ensure a tight engagement of two block elements.

Hearth arrangement for melting furnace

A method of combustion and a fluidized bed incinerator for burning and decomposing refuse such as municipal wastes are disclosed. The refuse is fluidized together with a fluidizing medium such as sand and primary air, to form a fluidized bed where the refuse is burned and decomposed. The pyrolysis gas produce by thermal decomposition of the refuse is combusted with secondary air supplied to the incinerator. By controlling the temperature inside the fluidized bed so as to be maintained in the range from 520.degree. to 650.degree. C., stable combustion is achieved, despite changes in the volume of refuse added to the fluidized bed, and the unburned pyrolysis gas and smut densities in the exhaust gas are decreased. Temperature control is achieved by spraying water onto the fluidized bed. The combustion air ratio can be reduced because the refuse can be stably combusted, and the temperature of pyrolysis gas inside the combustion chamber can be maintained at a high level.

Method and apparatus for stable combustion in a fluidized bed incinerator

A method of stable combustion in a fluidized bed incinerator for burning and decomposing refuse such as municipal wastes while fluidizing them is disclosed. A number of air diffuser tubes are provided inside the incinerator body for fluidizing the refuse and the fluidizing medium. The fluidizing air from the air diffuser tubes is supplied at high speed or low speed from each of the tubes respectively. By alternately forming more and less fluidized areas inside the fluidized bed, the refuse is stably burned. Because of the stable combustion of the refuse, the combustion air ratio can be reduced and the combustion chamber temperature inside the incinerator can be maintained at a high level.

Method of stable combustion for a fluidized bed incinerator

A method for combusting combustible gases generated by thermal decomposition of refuse in a fluidized bed incinerator is disclosed. The refuse is fluidized, together with a fluidizing medium such as sand, by the primary air, burned and decomposed. The pyrolysis gas produced by the decomposition of the refuse is completely burned by the secondary air introduced into the combustion chamber of the incinerator in a grid-shaped pattern, in multiple stages. The noncombustible gas and smut densities within exhaust gas are also reduced. Additionally, the combustion chamber temperature can be maintained at a high level as a result of the secondary combustion being carried out quickly.

Method of promoting secondary combustion in a fluidized bed incinerator

A method of catalystless denitrification for a fluidized bed incinerator to remove NOx generated in burning refuse such as municipal wastes as the refuse is fluidized in a fluidized bed incinerator is disclosed. The refuse is fluidized together with fluidizing medium such as sand along with primary air, and is thermally decomposed and/or burned. The combustible gases generated by pyrolysis are burned with the secondary air blown into the incinerator in a lattice work arrangement. A denitrification agent is mixed in a part of the secondary air, and the NOx present in the combustion gas is removed without using catalysts.

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Asaka, Japan

Satoshi Inoue