Flameless & Low NOx Combustion Patents: Leaders & Trends 2026
Flameless and Low NOx Combustion Furnace Patents: Who Leads and Where Filing Is Headed
31.3% sits with five filers. the top five assignees combine for 238 of the 760 records in scope, with a long tail of single- and few-filing entrants behind them. Filings rose from 14 in 2017 to a peak of 25 in 2023, then eased to 14 by 2024 — a 30% decline over the 2021-2024 window using the last fully comparable years. 2025 and 2026 figures are still filling in as publications catch up to filing dates.
- 1PRAXAIR TECH INC8.4%
- 2ZEECO INC8.2%
- 3AIR PROD & CHEM INC7.1%
- 4CLEARSIGN TECHNOLOGIES CORPORATION4.1%
- 5EDWARDS LTD3.6%
See the full flameless and low nox combustion in furnaces analysis in Eureka
- The complete ranking, not just the top five
- Every IPC branch with its share of the corpus
- The most-cited records, and where claim space is still thin
Common questions about this landscape
Who holds the most patents in low NOx and flameless combustion for furnaces?
One assignee leads the ranked field with 64 of the 760 records in scope, well ahead of the fifth-place company at 27. The top five assignees combined hold 238 records, or 31.3% of the total corpus, which is a real but not dominant concentration. The remaining records are spread across a long tail of smaller and single-filing entrants, so the field is not locked up by a handful of players.
Is patent filing in this space growing or slowing down?
Filing peaked in 2023 at 25 records and had eased to 14 by 2024, a 30% decline across that three-year window. That said, publication typically lags filing by around eighteen months, so 2025 and 2026 figures in this dataset are still incomplete and should not be read as confirmation the field is dying. The honest read is a pullback from a 2023 peak, not a collapse.
Which patent classes cover the most filing activity in furnace combustion?
F23D, covering burners, appears in 54.9% of the 760 records, and F23C, covering combustion apparatus generally, appears in 48.9%. Air and draught supply (F23L) is next at 22.0%, with furnace linings, combustion control, incineration and gas-turbine classes each in single digits to low double digits. Because a single record can carry several classifications, these shares add up to more than 100% and should not be summed.
Disclaimer. This analysis is based on Patsnap Eureka data drawn from a limited snapshot of global patent records and is provided for general information and reference only. Patent data carries inherent limitations — recent filings are under-counted because of publication lag, counts may be on a record or family basis, classification and applicant-name data may contain errors or duplicates, and the underlying search query defines the scope shown — so the analysis may be incomplete or inaccurate and may not reflect the full technology landscape.
Nothing here is an exhaustive prior-art, novelty, freedom-to-operate or validity search, nor does it constitute legal, financial or professional advice, and it should not be relied upon as such. Verify independently and review with qualified patent and legal professionals before acting on it.
Method: Filing trend and technology composition. Derived from a Patsnap search on Flameless and Low NOx Combustion in Furnaces covering 2015–2026, data cut-off 2026-07-31. Counts reflect published records only and shift as new filings publish. Every share divides by all records in scope. Data: Patsnap Eureka. See the full landscape report.