Abstract

In the method a carbonous fuel is carbonised at a high temperature to carbon and the carbon is activated physically with the aid of water vapour and/or carbon dioxide into activated carbon. Activated carbon is manufactured with a co-current gasifier meant for manufacturing product gas, which gasifier has a furnace (32). The fuel is carbonised into carbon and the carbon is activated into activated carbon in the furnace of the co- current gasifier. At least a part of the water vapour used in the activation of the carbon is formed by gasifying moist fuel, whereby water vapour is generated, which functions as an oxidising gas in the activation. Wood chips, which have a moisture content of 30-40 percent by weight, may be used as the fuel. In the same way at least a part of the carbon dioxide used in the activation of the carbon is formed in the gasification process of the fuel. The product gas generated in the gasification contains carbon dioxide, which functions in the activation process as an oxidising gas either on its own or together with water vapour. Activated carbon may be manufactured as a by-product of the manufacture of product gas. When gasifying solid fuel, fly ash, which is at least partly activated carbon, is generated as a by-product.

IPC Classes  ?

• C01B 31/08 - Active carbon
• C10J 3/26 - Arrangements or dispositions of valves or flues to permit flow of gases or vapours other than upwardly through the fuel bed downwardly

Abstract

In the method the gasification of solid fuel, such as wood chips, occurs with a co-current gasifier, which has a fuel silo (14), a combustion chamber (32) and a liquid channel (19) for circulating cooling liquid. The fuel is dispensed into the fuel silo, from where it flows into the combustion chamber, where combustion of the fuel occurs. The cooling liquid circulating in the liquid channel is used to limit the transfer of heat from the combustion chamber to the fuel silo and to thus prevent the heating and drying of the fuel in the fuel silo. The cooling liquid is led from the liquid channel to the bottom of the combustion chamber and from the bottom of the combustion chamber onwards out of the combustion chamber. At the bottom of the combustion chamber there is during the gasification continuously a layer of cooling liquid, in which the ash and coal particles generated in the combustion are mixed. The product gas generated in the gasification is led out of the combustion chamber along a flow duct (74b) of the cooling liquid and contaminants are removed from the product gas in a product gas washer (100). Also the ash and coal particles generated in the gasification are led out of the combustion chamber with the cooling liquid along the flow duct. The ash is removed from the cooling liquid in a coal separator (200) and the temperature of the cooling liquid is lowered with a condenser (300), after which the liquid is directed back into the liquid channel of the co-current gasifier.

IPC Classes  ?

• C10J 3/26 - Arrangements or dispositions of valves or flues to permit flow of gases or vapours other than upwardly through the fuel bed downwardly
• C10B 53/02 - Destructive distillation, specially adapted for particular solid raw materials or solid raw materials in special form of cellulose-containing material

Abstract

A grate structure (20) for a furnace comprises a grate (38), which has holes (42) for the passing through of gaseous substances and ash. On the first side of the grate there is a dome-shaped lid part, which is dimensioned to cover the grate at least partly. The lid part prevents the holes of the grate from clogging, whereby the gaseous substances can flow continuously through the grate. A flow channel (26) passes through the grate, in which flow channel there is a support axis (40) for supporting the lid part. On the second side of the grate there is a trough-like bottom part (22) surrounding the flow channel. There is a first ring-shaped gap (32) between the edge of the bottom part and the edge of the lid part and there is a second ring-shaped gap (34) between the edge of the lid part and the wall of the flow channel, into which second ring-shaped gap the grate is fitted. The gaseous substances can flow via the first gap underneath the grate and via the second gap through the grate above the grate to the space between the lid part and the grate. From this space the gaseous substances exit along the flow channel. The grate structure is advantageously the grate structure of the furnace of a co- current gasifier.

IPC Classes  ?

• F23H 13/08 - Grates specially adapted for gas generators and also applicable to furnaces
• F23H 17/00 - Details of grates
• C10J 3/34 - GratesMechanical ash-removing devices
• F24B 1/193 - GratesIrons
• F24B 13/02 - Arrangement or mounting of fire-grate assembliesArrangement or mounting of linings for fire-boxes, e.g. fire-backs

Abstract

15 Abstract The co-current gasifier has a fuel silo (14) for storing the fuel to be gasified, such as the wood chips. The bottom of the fuel silo is made up of the upper floor (16a), underneath which there is at least one gasification compartment (20) for gasifying the fuel. The gasification compartment has a combustion chamber, which has a triple wall structure comprising an internal jacket, an intermediate jacket and an external jacket. The upper floor has several holes (30) for conducting the fuel from the fuel silo to the gasification compartment/gasification compartments. The gasification of the fuel takes place in a small area between the lower part of the fuel silo and the upper part of the gasifier. The gasifier may have several gasification compartments, whereby the upper floor has one hole leading from the fuel silo to the gasification compartment for each gasification compartment. Preferably the gasification compartments are situated in a ring-like manner underneath the upper floor. Between the gasification compartment and the upper floor there is a ring-like cooling channel (18), through which the gasification air is conducted into the gasification compartment.In an embodiment of the invention there is further a lower floor and only one gasification compartment, which is situated underneath the lower floor. The upper and lower floors limit between them a cooling space, through which several concentric holes lead.

IPC Classes  ?

• C10J 3/26 - Arrangements or dispositions of valves or flues to permit flow of gases or vapours other than upwardly through the fuel bed downwardly
• C10J 3/30 - Fuel charging devices

Abstract

The invention relates to a method for gasifying solid fuel in a co-current gasifier having a fuel silo (14) and a combustion chamber (32). The method comprises a pyrolysis phase in which the fuel decomposes into pyrolysis products, and a gasification phase in which the pyrolysis products are gasified into product gas. Heat transfer from the combustion chamber (32) to the fuel silo (14) is restricted in the method. This is to ensure that the fuel does not dry and pyrolysis does not take place in the fuel silo. The beginning of the pyrolysis is intentionally transferred as close to the gasification phase as possible, and an attempt is made to make the duration of the pyrolysis phase as short as possible. The rise of the fuel temperature is slowed down by transferring heat generated in the gasification phase to a medium, such as gasification air. In the co-current gasifier according to the invention, between the fuel silo and the combustion chamber, there is a cooling channel (18), which restricts the transfer of heat and also functions as a preheater for the gasification air. The gasifier has an upper floor (16a), which forms the upper surface of the cooling channel, and a lower floor (16b) forming the lower surface of the cooling channel, and the fuel silo is placed above the upper floor and the combustion chamber below the lower floor. The combustion chamber of the gasifier comprises an internal jacket (34), an intermediate jacket (36), an external jacket (38) and a grate (40). The gasification air is arranged to be conducted to the combustion chamber through a space between the intermediate jacket and the external jacket.

IPC Classes  ?

• C10J 3/66 - Processes with decomposition of the distillation products by introducing them into the gasification zone
• C10J 3/74 - Construction of shells or jackets
• C10B 49/06 - Destructive distillation of solid carbonaceous materials by direct heating with heat-carrying agents including the partial combustion of the solid material to be treated with hot gases or vapours, e.g. hot gases obtained by partial combustion of the charge while moving the solid material to be treated according to the "moving bed" technique
• C10B 53/02 - Destructive distillation, specially adapted for particular solid raw materials or solid raw materials in special form of cellulose-containing material