F23C METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN AIR
Introduced: September 1968
Classification Context
- Section:
- MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- Class:
- COMBUSTION APPARATUS; COMBUSTION PROCESSES
- Subclass:
- METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN AIR
Description
This subclass covers combustion systems and methods employing liquid fuels or finely divided solid fuels (such as coal dust or pulverized fuel) dispersed and burned in air streams. It encompasses burner designs, fuel injection systems, and combustion chamber configurations optimized for suspension-type combustion, particularly relevant to oil-fired boilers, pulverized coal furnaces, and similar industrial heating applications. The classification excludes gas combustion (covered under F23D) and combustion of solid fuels in fixed or moving beds (covered under F23B), focusing instead on systems where fuel particles or droplets remain airborne during the combustion process.
Filing statistics
IPC subclass F23C recorded 19,304 patent applications worldwide between 2013 and 2023. Annual filings declined from 1,668 in 2013 to 1,524 in 2023 (-9%), peaking at 1,986 applications in 2017. The most active applicants in class F23 are GE (GENERAL ELECTRIC COMPANY) (2,124 applications), XIAN THERMAL POWER RESEARCH INSTITUTE COMPANY (1,369 applications) and NINGBO FOTILE KITCHENWARE COMPANY (1,363 applications).
Source: EPO PATSTAT, worldwide filings
In class comparison
F23C ranks 5th of 12 subclasses with filings in F23, with 19,304 applications between 2013 and 2023, 6.4% of the class. Annual filings declined 9% from 2013 to 2023, below the class as a whole (+76%).
| Rank | Subclass | Title | Applications | Share |
|---|---|---|---|---|
| 1 | F23J, Removal or Treatment of Combustion Products or Combustion Residues; Flues | Removal or Treatment of Combustion Products or Combustion Residues; Flues | 62,845 | 20.9% |
| 2 | F23G, Cremation Furnaces; Consuming Waste or Low Grade Fuels by Combustion | Cremation Furnaces; Consuming Waste or Low Grade Fuels by Combustion | 62,605 | 20.8% |
| 3 | F23D, Burners | Burners | 48,008 | 15.9% |
| 4 | F23L, Supplying Air or Non-Combustible Liquids or Gases to Combustion Apparatus in General; Valves or Dampers Specially Adapted for Controlling Air Supply or Draught in Combustion Apparatus; Inducing Draught in Combustion Apparatus; Tops for Chimneys or Ventilating Shafts; Terminals for Flues | Supplying Air or Non-Combustible Liquids or Gases to Combustion Apparatus in General; Valves or Dampers Specially Adapted for Controlling Air Supply or Draught in Combustion Apparatus; Inducing Draught in Combustion Apparatus; Tops for Chimneys or Ventilating Shafts; Terminals for Flues | 24,279 | 8.1% |
| 5 | F23C | Methods or Apparatus for Combustion Using Fluid Fuel or Solid Fuel Suspended in Air | 19,304 | 6.4% |
| 6 | F23R, Generating Combustion Products of High Pressure or High Velocity, e.g. Gas-Turbine Combustion Chambers | Generating Combustion Products of High Pressure or High Velocity, e.g. Gas-Turbine Combustion Chambers | 17,458 | 5.8% |
| 7 | F23K, Feeding Fuel to Combustion Apparatus | Feeding Fuel to Combustion Apparatus | 17,228 | 5.7% |
| 8 | F23N, Regulating or Controlling Combustion | Regulating or Controlling Combustion | 15,400 | 5.1% |
| 9 | F23Q, Ignition; Extinguishing Devices | Ignition; Extinguishing Devices | 12,442 | 4.1% |
| 10 | F23B, Methods or Apparatus for Combustion Using Only Solid Fuel | Methods or Apparatus for Combustion Using Only Solid Fuel | 9,943 | 3.3% |
Source: EPO PATSTAT, worldwide filings
Additional Content
Glossary
air a mixture of gases containing free oxygen and able to promote or support combustion primary air air supplied to the burning fuel (e.g. together with the fuel) in order to liberate combustible gases secondary air air supplied to the combustible gases liberated by the primary air in order to complete their combustion. The expression "secondary air" covers "tertiary air" etc. Burner burners 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 burner includes the means for feeding air that are arranged in immediate connection with a fuel feeding conduit, for example concentric with it. Combustion 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 combustion chamber combustion chambers a chamber in which fuel is burned to establish a self-supporting fire or flame and which surrounds that fire or flame combustion zone the part of an apparatus where the reaction takes place between air and fuel
Limiting references
Burners Candles
Application references
Baking ovens Cooking apparatus Gas turbine plants Lighting Generating steam Combustion specially adapted for waste or low grade fuel Generating combustion products of high temperature or high pressure Domestic stoves or ranges for cooking or local heating Domestic heating systems or space-heating systems Heating of fluids, e.g. air or water Drying Heat treatment of material or articles
Related Keywords
11 direct subcodes
Child Classifications
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- F23C 1/00 Combustion apparatus specially adapted for combustion of two or more kinds of fuel simultaneously or alternately, at least one kind of fuel being either a fluid fuel or a solid fuel suspended in air
- F23C 10/00 Apparatus in which combustion takes place in a fluidised bed of fuel or other particles
- F23C 101/00 Combustion in entrained fluidised beds, i.e. fluidised beds which have no distinct upper surface
- F23C 13/00 Apparatus in which combustion takes place in the presence of catalytic material
- F23C 15/00 Apparatus in which combustion takes place in pulses influenced by acoustic resonance in a gas mass
- F23C 3/00 Combustion apparatus characterised by the shape of the combustion chamber
- F23C 5/00 Combustion apparatus characterised by the arrangement or mounting of burners
- F23C 6/00 Combustion apparatus characterised by the combination of two or more combustion chambers
- F23C 7/00 Combustion apparatus characterised by arrangements for air supply
- F23C 9/00 Combustion apparatus characterised by arrangements for returning combustion products or flue gases to the combustion chamber
- F23C 99/00 Subject matter not provided for in other groups of this subclass
Top Applicants
Top 10 applicants by patent filingsfor class F23, 2013–2023, worldwide · Source: EPO PATSTAT
- GE (GENERAL ELECTRIC COMPANY) US 2,124
- XIAN THERMAL POWER RESEARCH INSTITUTE COMPANY 1,369
- NINGBO FOTILE KITCHENWARE COMPANY 1,363
- SIEMENS DE 997
- UNITED TECHNOLOGIES CORPORATION (UTC) US 937
- GE (GENERAL ELECTRIC COMPANY) 898
- VATTI 815
- CHINESE ACADEMY OF SCIENCES 719
- RINNAI COMPANY 708
- MITSUBISHI HITACHI POWER SYSTEMS 670