F23B - Definition 
Definition statement
This subclass covers:
General function-oriented aspects of methods and apparatus for combustion of solid fuel wherein the main body of fuel is either
- essentially stationary during combustion; or
- mechanically transported, as opposed to pneumatically transported or suspended in air, during combustion;
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 large subject matter areas
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
- of general interest for combustion of different types of solid fuel, for example not specially adapted for a particular fuel; or
- specially adapted for specific solid fuels other than those provided for in F23G (see the list below), for example "normal" commercial fuel, such as coal, firewood, wood chips, wood pellets or straw.
Classification is made in F23G if a method or apparatus is specially adapted for combustion of any of the following types of substances:
- Human corpses or amputated body parts;
- Animal carcasses or their discarded body parts;
- Fuels, e.g. waste, presenting particular fuel-related environmental problems requiring specially adapted methods or apparatus for combustion, for example toxic, explosive, radioactive or corrosive fuels;
- Waste having a special physical form requiring specially adapted methods or apparatus for combustion, for example packaged waste, rubber tyres or discarded cars;
- Low-grade fuels presenting particular problems of combustion requiring specially adapted methods or apparatus for combustion, for example fuels containing high amounts of water or other non-combustible substances;
- Fuels that vary considerably in composition or form and therefore require specially adapted methods or apparatus for combustion;
- Household, municipal, or similar waste that is solely or primarily burned for the purpose of its destruction.
Subclass F23R (Generating combustion products of high pressure or high velocity), especially group F23R 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 (for example of 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.
References relevant to classification in this subclass
This subclass does not cover:
Combustion of both solid fuel and fluid fuel, simultaneously or alternately | F23C 1/00, F23D 17/00 |
Combustion of solid fuel suspended in a stream of air, e.g. combustion in fluidised beds or combustion of pulverised fuel using burners where the fuel is transported into the combustion chamber by an air stream | F23C, F23D 1/00 |
Combustion of solid fuel suspended in a liquid, e.g. combustion of coal-water slurry | F23C, F23D |
Combustion of fuels that are solid at room temperatures, but burned in melted form, e.g. candle wax | C11C 5/00, F23C, F23D |
Baking ovens | A21B |
Cooking apparatus | A47J |
Lighting | F21 |
Generating steam | F22B |
Combustion specially adapted for waste or low grade fuel | F23G |
Generating combustion products of high temperature or high pressure | F23R |
Domestic stoves or ranges for cooking or local heating | F24B, F24C |
Domestic heating systems or space-heating systems | F24D |
Heating of fluids, e.g. air or water | F24H |
Drying | F26B |
Heat treatment of material or articles | F27 |
Informative references
Attention is drawn to the following places, which may be of interest for search:
Places for details of general applicability for combustion apparatus Grates, cleaning or raking of grates F23H Removal or treatment of combustion products (e.g. flue gases) or combustion residues (e.g. ash) F23J Feeding fuel F23K Supplying air or other non-combustible liquids or gases (e.g. water or steam) F23L Constructional details of combustion chambers, not otherwise provided for F23M Regulating or controlling combustion F23N Ignition F23Q Other places Chemical or biological purification of waste gases B01D 53/34 Chemical or physical processes or apparatus in general B01J Heat-producing reactions of chemical substances, other than combustion (e.g. of hydrogen peroxide and methane, or iron oxide and aluminium) C, F24V 30/00 Combustionapparatus using fluid fuel or solid fuel suspended in air F23C Burners for fluid fuel or solid fuel suspended in air F23D Special rules of classification 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 the advanced level in this subclass it is desirable to add the indexing codes of groups F23B 101/00-F23B 103/02.
Glossary of terms In this subclass, the following terms or expressions are used with the meaning indicated: a mixture of gases containing free oxygen and able to promote or support combustion air supplied to the burning fuel in order to liberate combustible gases air supplied to the combustible gases liberated by the primary air in order to complete their combustion. The term "secondary air" covers "tertiary air" etc. means any solid combustion residues, for example remaining in the fuel bed or suspended in the flue gases a device by which fluid fuel or solid fuel suspended in air is passed to a combustion space where it burns to produce a self-supporting flame a heat-producing sequence of chemical reactions between a burnable substance and molecular oxygen, e.g. in air, in most cases generating light in the form of flames or a glow a chamber in which fuel is burned to establish a self-supporting fire or flame and which surrounds that fire or flame the part of the apparatus where the reaction takes place between air and fuel any gaseous products of combustion a perforated surface (e.g. a grid) which supports or delimits a bed of burning fuel and serves to supply primary air
Synonyms and Keywords In patent documents the expression "burner" is often used with the meaning of "combustion apparatus".
air
primary air
secondary air
ash
Burner
Combustion
combustion chamber
combustion zone
flue gases
grate