General function-oriented aspects of methods and apparatus for combustion of solid fuel wherein the main body of fuel is either

and wherein the combustion does not involve liquid or gaseous fuels, or pulverulent fuel burned in suspension.

The solid fuel can be in the form of lumps or pieces, e.g. coal, briquettes or firewood, or pulverulent or granulated, e.g. coal powder, wood pellets or wood chips.

Relationship between this subclass and application subclasses of class F23.

Subclass F23G, Cremation furnaces; Consuming waste by combustion is to be seen as an application place in relation to the function-oriented aspects of this subclass. In case of doubt, classification should be made in both subclasses, or in both F23G and detail subclasses of class F23.

Classification is made in this subclass if the method or apparatus is:

Classification is made in F23G if a method or apparatus is specially adapted for combustion of any of the following types of substances:

Subclass F23R, Generating combustion products of high pressure or high velocity, especially group F23B 5/00, is also to be seen as an application place in relationship to this subclass. Classification is made in F23R if the apparatus or method is specially adapted for generating combustion products of high pressure or high velocity.

Relationship between this subclass and other application places.

Combustion of solid fuel is often used for purpose of heating or performing different operations. Apparatus for combustion of solid fuel can be self-contained devices, but are often part of, or used in connection with, heat-consuming apparatus, such as heating boilers. This subclass is therefore related to several places providing for uses of heat. In many of these fields the solid fuel combustion apparatus can be considered a detail of a bigger entity. A non-exhaustive list of examples of such classes or subclasses will be found under the heading "Informative references" below.

Combinations of combustion apparatus with other apparatus, where the combustion apparatus can be seen as a detail of the complete apparatus, e.g. a steam boiler, are classified as a whole, in the place for the other apparatus. Additional classification is made in this subclass only if features relating to the combustion apparatus per se are of interest apart from its application.

Relationship between this subclass and detail subclasses of class F23.

Subclasses F23H - F23Q are to be seen as detail places in relation to this subclass. Classification is made in this subclass if the apparatus as a whole is of interest or if a detail is of use only for a particular type of combustion apparatus and not specifically provided for in any of subclasses F23H - F23Q. If a detail of a combustion apparatus is of interest, classification is made in the relevant subclass providing for such matter.

Relationship between this subclass and places for gasification or destructive distillation.

C10B covers destructive distillation of carbonaceous material for production of gas, coke, tar or similar matter.

C10J covers production of combustible gases containing carbon monoxide from solid carbonaceous fuels.

Classification is made in these subclasses if the combustible substances produced, e.g. gases or coke, are burned in an apparatus separate from the gasification or distillation apparatus.

Classification is made in this subclass if complete combustion takes place in the same apparatus as the gasification, for example in different parts of the same combustion chamber or in an afterburner immediately connected to a primary combustion chamber.

In this subclass, the first place priority rule is applied, i.e. at each hierarchical level, classification is made in the first appropriate place.

In this subclass methods are classified in the groups that cover the apparatus used. Methods that are of general applicability are classified in group F23B 90/00.

When classifying in this subclass, add the Indexing Codes:

F23B 2101/00;

F23B 2103/00-F23B 2103/02;

F23B 2900/00001 -F23B 2900/99001.

Combustion apparatus using only lump fuel.

F23B 1/00 - F23B 1/12 are not used anymore for classification, please refer to groups F23B 10/00 - F23B 99/00 instead.

Combustion apparatus which is portable or removable with respect to the boiler or other apparatus which is heated.

F23B 3/00 is not used anymore for classification, please refer to groups F23B 10/00 - F23B 99/00 instead.

Combustion apparatus with arrangements for burning uncombusted material from primary combustion.

F23B 5/00 - F23B 5/04 are not used anymore for classification, please refer to groups F23B 10/00 - F23B 99/00 instead.

Combustion techniques; Other solid-fuel combustion apparatus.

F23B 7/00 - F23B 7/007 are not used anymore for classification, please refer to groups F23B 10/00 - F23B 99/00 instead.

Combustion apparatus characterized by the combination of two or more combustion chambers.

Combustion apparatus including two or more combustion chambers in which one of the combustion chambers works as a secondary combustion chamber.

Combustion apparatus including two or more physically separated combustion zones, e.g. by a perforated partition wall in a single enclosure in which one of the combustion zones works as a secondary combustion chamber.

Combustion apparatus using e.g. rotary, vibrating or travelling grates, reciprocating bars or pushers, rocking bars, screw conveyors or any other means located inside the combustion chamber for agitating or advancing the fuel.

Combustion apparatus using e.g. throwing devices, reciprocating pushers, screw conveyors or other driven means located outside the combustion chamber for supplying fuel directly into the combustion chamber.

Combustion apparatus using gravity as sole means for feeding the fuel into the combustion zone.

Combustion apparatus wherein the fuel is loaded on a grate or on a support on which it rests till complete exhaustion without further move or agitation.

Combustion apparatus wherein solid combustion residues, e.g. ashes or fly-ashes are returned to the chamber for complete burning.

Combustion apparatus having either means guiding the flue gas along specific path, e.g. for increasing heat transfer to the heat recovery means or creating longer permanence time of the gases in the combustion chamber, or for flue gas recirculation.

Methods for starting the combustion, for staged combustion, i.e. a first combustion in a oxidant deficient atmosphere followed by secondary combustion in oxidant rich atmosphere, or for catalytic combustion.

Among combustion methods including secondary combustion, those involving gasification or pyrolysis in a reductive atmosphere in the primary zone, and, involving combustion in an oxidative atmosphere in the secondary zone.