Wet Flue Gas Desulfurization Patents: Who Leads & Where Gaps Are 2026
- 46.6% concentration at the top. The five leading assignees account for 392 of the 842 records in scope — a field where claim space near the core absorber and scrubbing chemistry is already dense.
- Filing has cooled from its 2018 peak. Annual filings ran from 55 at the 2018 peak down through a documented -50% drop between 2021 (10) and 2024 (5), the last year publication lag lets us call complete.
- B01D dominates, but adjacent classes lag far behind. 86.5% of records touch separation processes (B01D), while wastewater treatment (C02F, 5.1%) and analysis/testing (G01N, 2.7%) remain comparatively open.
Filing growth compares 2021 (10 records) with 2024 (5) — a three-year span. 2024 is the most recent year we treat as complete: publication lags filing by roughly 18 months, so 2025 onwards are still filling in and any growth rate that ends there would understate the field. Top-5 share is the combined record count of the five largest assignees divided by all 842 records in scope (CR5), not by the ranked leaders only.
What this landscape covers
Wet flue gas desulfurization (WFGD) removes sulfur dioxide from combustion exhaust by contacting flue gas with a limestone or lime slurry inside an absorber tower, producing gypsum as a saleable byproduct. The patent record in scope spans 842 published families filed between 2015 and the 2026 cut-off, covering absorber design, liquid-to-gas ratio control, oxidation air injection, mist elimination and the wastewater streams the process generates. Because a single filing can touch several of these sub-processes at once, the technology composition below is read by IPC subclass share rather than as a simple ranked list.
The assignee base is short at the top and long at the tail: a handful of power-equipment and environmental-technology firms hold the largest blocks of filings, while the remainder of the ranked 100 companies each hold single-digit counts. Reading the filing trend alongside receiving-office data shows where enforcement risk is concentrated and where the process chemistry is still open to new claims.
Let an AI agent run this analysis on your own technology
Pick a task. Every answer cites the patents behind it.
Filing trends and technology composition
Two views of the same 842-record dataset: the year-by-year filing count, and the IPC subclasses those records fall under.
Filing trend, 2017-2026
Annual filings rose to a peak of 55 in 2018, then fell; the documented span from 10 filings in 2021 to 5 in 2024 marks a -50% decline over the last three-year window that publication lag allows us to treat as complete. 2025 and 2026 figures are still filling in and should not be read as a continued decline.
IPC subclass composition
B01D (separation processes) appears in 86.5% of the 842 records, confirming that most filings anchor on the core scrubbing/absorption mechanism. Control systems (G05B, G05D combined at 10.8% and 6.5%) and wastewater treatment (C02F, 5.1%) sit well behind, and material analysis (G01N, 2.7%) is the thinnest class tracked.
Shares are the percentage of the 842 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Wet Flue Gas Desulfurization with Eureka
This page is one run against one query. Ask Eureka your own question about wet flue gas desulfurization and every answer comes back with the patent numbers behind it.
Try EurekaMost-cited records in this landscape
US9457316B2 — Method for controlling compounds and conditions in a wet flue gas desulfurization (WFGD) unit
Filed by The Babcock & Wilcox Company and granted in 2016, this patent covers supplying a reducing agent to absorber slurry to lower oxidation-reduction potential, addressing corrosion and precipitation issues inside the WFGD scrubber loop.Abstract condensed from the original filing for readability.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US5672323A | Activated carbon flue gas desulfurization systems for mercury removal | 212 |
| 2 | US5787821A | High velocity integrated flue gas treatment scrubbing system | 117 |
| 3 | US20070142975A1 | Model based optimization of a single or multiple power generating units | 112 |
| 4 | US20090162269A1 | Reduced liquid discharge in wet FLUE gas desulfurization | 104 |
| 5 | US5246471A | Method and apparatus for gas liquid contact | 99 |
| 6 | US20110052453A1 | Removal of carbon dioxide from a flue gas stream | 83 |
| 7 | US7117046B2 | Cascaded control of an average value of a process parameter to a desired value | 81 |
| 8 | US7113835B2 | Control of rolling or moving average values of air pollution control emissions to a desired value | 79 |
| 9 | US6550751B1 | Gas-liquid contactor with liquid redistribution device | 68 |
| 10 | US5512072A | Flue gas scrubbing apparatus | 61 |
Citation counts favor older filings simply because they have had longer to accumulate references; treat this as a signal of influence within the searched corpus, not a ranking of current commercial importance.
Each row carries its publication number; clicking a row searches Eureka by that number.
Put your own technology through the same analysis
Eureka on the web
When you want the answer in the next five minutes.
The agent works the prompt against patents and technical literature, citing every source.
Run your analysis now →MCP server & REST API
When it has to run inside your own pipeline.
Patent search, landscape analysis and assignee resolution as MCP tools. Drop them into any agent framework, or call REST directly.
Browse MCP servers →What the numbers mean for filing strategy
Three read-throughs from the concentration, trend and classification data above.
The core absorber chemistry is claimed territory
With 392 of 842 records held by the five leading assignees, new entrants targeting the central limestone-gypsum scrubbing mechanism are filing into dense prior art. The tenth-ranked assignee alone holds 19 records, meaning the concentration extends well past the top five.
Filing activity has cooled from its 2018 peak
After peaking at 55 filings in 2018, annual counts fell to 10 by 2021 and 5 by 2024 — a documented -50% drop across that span. This does not necessarily mean interest has dropped; it may reflect a maturing core design with fewer novel claims left to stake near the absorber itself.
Wastewater and analysis claims are comparatively thin
Only 43 of 842 records carry a C02F wastewater-treatment classification and just 23 carry G01N material analysis, versus 728 records touching B01D separation processes. That gap is where the process's byproduct and monitoring problems remain less thoroughly claimed.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to wet flue gas desulfurization, with the prior art for and against each one.
Who holds the ground, and what is left open
A short list of large power-equipment and environmental-technology firms holds the majority of filings; recent-year activity from those same leaders has slowed to zero in the latest tracked year, which is consistent with the broader -50% momentum decline rather than any single company exiting the field.
A single assignee holds the largest block
The top-ranked assignee holds 99 of the 842 records in scope, well ahead of the fifth-place holder at 48 and the tenth-place holder at 19 — a steep drop-off that marks this as a concentrated rather than fragmented field.
Below the leaders, filings thin out fast
The ranked list covers 100 companies, but combined top-10 share is 62.6% of all 842 records, meaning the remaining 90-plus ranked entities split the rest — mostly in single digits each.
Co-filing is limited and concentrated
Only 10 co-assignee pairs appear in the dataset, with the strongest pairing linking Alstom Technology with an individual inventor at 4 shared records. Co-filing activity here is a minor pattern next to solo corporate filing.
| Assignee | Recent year | YoY |
|---|---|---|
| Alstom Technology Ltd | 0 | — |
| Marsulex Environmental Technologies Corp | 0 | — |
| Babcock Hitachi K.K. | 0 | — |
| The Babcock & Wilcox Company | 0 | — |
| Mitsubishi Heavy Industries, Ltd. | 0 | — |
| Babcock & Wilcox Power Generation Group, Inc. | 0 | — |
| General Electric Technology GmbH | 0 | — |
| General Electric Company | 0 | — |
Where to take this analysis
The dataset points to specific next steps depending on whether you are scoping freedom-to-operate or looking for a filing angle.
Check freedom-to-operate against the top holders
With 46.6% of records held by five assignees, any absorber-tower or core scrubbing claim should be checked against those portfolios before drafting.
Run a freedom-to-operate searchScope the under-claimed branches
Wastewater integration, mist eliminator monitoring and oxidation air control all show thinner IPC coverage than the core separation process — each is a narrower place to stake a first claim.
Explore white space in EurekaCommon questions about this landscape
The dataset ranks 100 companies by filing count, and the leading assignee holds 99 of the 842 records in scope. The top five combined account for 392 records, or 46.6% of the field, with a steep drop to 48 records at fifth place and 19 at tenth. This is a concentrated field: large power-equipment and environmental-technology firms with long operating histories in flue gas treatment hold most of the core scrubbing and absorber claims, leaving the long tail of ranked companies with single-digit counts each.
No — filings peaked at 55 in 2018 and have since declined, with a documented drop from 10 filings in 2021 to 5 in 2024, a -50% fall over that span. 2024 is the most recent year with a reasonably complete count; 2025 and 2026 figures are still filling in because publication lags filing by roughly 18 months. A slowing filing rate near the core mechanism does not necessarily mean the technology is stagnant — it more often means the central absorber and scrubbing chemistry are already densely claimed, pushing new activity toward adjacent processes.
The dominant class is B01D, separation processes including filtration, appearing in 86.5% of the 842 records in scope — confirming that nearly all filings touch the core scrubbing or absorption mechanism in some way. Control and regulating systems (G05B, G05D) cover 10.8% and 6.5% of records respectively, water and wastewater treatment (C02F) covers 5.1%, and material analysis and testing (G01N) covers just 2.7%. Because records can carry multiple IPC classes, these shares add to more than 100% and should not be summed.
US9457316B2, assigned to The Babcock & Wilcox Company, covers a method of supplying a reducing agent to the absorber slurry in a WFGD scrubber to lower the oxidation-reduction potential and control corrosion and precipitation within the system. Anyone designing a slurry-chemistry control method that manages ORP through reducing-agent dosing in an absorber loop should review this claim scope closely before finalizing a design. It does not block WFGD systems generally, or absorber designs that manage corrosion through other mechanisms such as materials selection or mechanical design rather than slurry chemistry.
The clearest gaps sit outside the core separation process: wastewater treatment and zero-discharge integration (C02F, 5.1% of 842 records), material analysis and monitoring methods (G01N, 2.7%), and specific sub-processes such as mist eliminator fouling detection and real-time liquid-gas ratio sensing that sit within thinly represented classes. These branches carry meaningfully lower record density than the 86.5%-covered B01D core, which is where most of the leading assignees' portfolios are concentrated. A first claim in these areas is more likely to clear prior art than one filed against the central absorber or scrubbing mechanism.
Research Wet Flue Gas Desulfurization in depth with Eureka
Go past this page: query the whole wet flue gas desulfurization corpus yourself, in your own scope.
Every answer comes back with patent numbers you can open.
Disclaimer. This page is generated from Patsnap Eureka data drawn from a limited snapshot of global patent and scientific-literature records, and is provided for general information and reference only.
Patent data carries inherent limitations: recent filings (typically the most recent 18–24 months) are under-counted due to standard publication lag; counts may be reported at either a patent-family or a patent-record basis and are not always directly comparable; classification, applicant-name, and citation data may contain errors, duplicates, or omissions; and the underlying search query defines and constrains the scope shown. As a result, the analysis may be incomplete or inaccurate and may not reflect the full technology landscape.
Nothing on this page constitutes an exhaustive prior-art, novelty, freedom-to-operate, or validity search, nor does it constitute legal, financial, investment, or professional advice, and it should not be relied upon as such. Any patent, commercial, or strategic decision should be verified independently and reviewed with qualified patent, legal, and domain professionals. Patsnap makes no warranties, express or implied, as to the accuracy, completeness, or fitness for any particular purpose of the information presented.
Machine translation. Assignee and organisation names originally recorded in Chinese, Japanese or Korean have been rendered into English by an AI translation step so that the tables stay readable. These renderings are best-effort and may not match a company’s registered English name; the original name is what the underlying patent record carries, and it is what any Eureka query launched from this page uses.