IP Verse

Sorbents For The Oxidation And Removal Of Mercury

Patent No. US10926218 (titled "Sorbents For The Oxidation And Removal Of Mercury") was filed by Birchtech Corp on Jul 11, 2019.

What is this patent about?

’218 is related to the field of removing mercury from flue gas, specifically flue gas produced by coal combustion. The background problem is that burning coal releases mercury into the atmosphere, which needs to be controlled. Existing methods, such as injecting activated carbon, are not fully effective, especially for elemental mercury, and can be expensive and create waste disposal issues.

The underlying idea behind ’218 is to enhance mercury capture by adding iodine or iodide salts to the coal before combustion or directly into the combustion chamber. This additive reacts with the activated carbon sorbent injected downstream, improving its ability to capture mercury from the flue gas. The key is to use a specific ratio of the iodine additive to the amount of sorbent injected.

The claims of ’218 focus on a method of separating mercury from mercury-containing gas produced by coal combustion. The method involves adding HI, an iodide salt, or a combination to the coal or combustion chamber, injecting activated carbon sorbent downstream, contacting the mercury with the sorbent, and separating the sorbent. A key element is the weight ratio of the iodine additive to the sorbent , which is specified as being between 1:100 and 30:100.

In practice, the iodine additive is introduced either with the coal before it enters the combustion chamber or directly into the combustion chamber itself. The activated carbon sorbent is then injected into the flue gas downstream. The iodine additive is believed to react with the activated carbon, creating a 'promoted sorbent' that is more effective at capturing mercury. The spent sorbent is then separated from the flue gas, typically using a baghouse or electrostatic precipitator.

The patent also describes a feedback mechanism where the mercury content of the cleaned flue gas is measured, and this measurement is used to adjust the injection rate of the sorbent or the amount of iodine additive used. This allows for optimization of the process based on real-time conditions. This approach differs from prior solutions by pre-treating the coal or combustion chamber with iodine, rather than relying solely on the properties of the injected activated carbon.

How does this patent fit in bigger picture?

Technical landscape at the time

In the early 2000s when ’218 was filed, mercury removal from flue gas streams was typically implemented using sorbent injection, where fine particles of materials like activated carbon were introduced into the gas stream. At a time when hardware or software constraints made real-time monitoring and control of sorbent injection non-trivial, systems commonly relied on fixed sorbent-to-mercury ratios, which often resulted in inefficient sorbent usage and disposal challenges.

Novelty and Inventive Step

The examiner agreed with the applicant's description of how the amended claims are different from the existing prior art. The prior art does not describe or suggest using a weight ratio of HI or iodide salt added to the coal and/or combustion chamber, to an amount of injected sorbent is from about 1:100 to about 30:100, in combination with the other recited process steps. The examiner withdrew the outstanding double patenting and new matter rejections.

Claims

This patent contains 26 claims, with independent claims 1, 25, and 26 directed to methods of separating or reducing mercury from a mercury-containing gas produced by coal combustion with added HI or iodide salt. The dependent claims generally elaborate on the conditions, components, and parameters of the methods described in the independent claims.

Key Claim Terms New

Definitions of key terms used in the patent claims.

Term (Source)Support for SpecificationInterpretation
Activated carbon
(Claim 1, Claim 25, Claim 26)		“Fine-particle injection sorbents include activated carbon, metal oxide sorbent, sodium sulfide particles, and basic silicate or oxide sorbents. When particle injection is employed, the mercury chemisorbed to the sorbent particle is removed from the gas stream in a bag house or ESP and collected along with ash particulates (for example, see U.S. Pat. Nos. 4,889,698, 4,956,162, 5,672,323, 5,827,352, 6,027,551, and 5,505,766).”A carbon-based material with a high surface area, used as a sorbent to capture mercury from a gas stream.
Combustion chamber
(Claim 1, Claim 25, Claim 26)		“The combustion and gasification of fossil fuel such as coal generates flue gas that contains mercury and other trace elements that originate from the fuel. Burning fossil fuels generates a flue gas that contains mercury (and other trace elements) that was in the coal, plus oxides of sulfur and nitrogen (acid gas emissions) and particulates whose release to the environment must be controlled by use of sorbents, scrubbers, filters, precipitators, and other removal technologies.”A chamber where coal is burned to produce energy and a mercury-containing gas.
Iodide salt
(Claim 1, Claim 25, Claim 26)		“Other additives of base chemistry (Ca, Na, and others) may be added to flue gas as a sorbent mixture, or co-injected to selectively sorb acid gases or other flue gas constituents to keep available reactive sites for mercury oxidation and subsequent capture.”A salt containing iodide ions, added to coal or a combustion chamber to enhance mercury removal.
Mercury-containing gas
(Claim 1, Claim 25, Claim 26)		“The combustion and gasification of fossil fuel such as coal generates flue gas that contains mercury and other trace elements that originate from the fuel. The release of the mercury (and other pollutants) to the environment must be controlled by use of sorbents, scrubbers, filters, precipitators, and other removal technologies.”A gas stream produced by combusting coal, which contains mercury as a pollutant.
Promoted sorbent
(Claim 26)		“A halogen/halide promoted activated carbon sorbent is described that is highly effective for the removal of mercury from flue gas streams. The sorbent comprises a new halide-modified carbon form containing a reactive compound produced by the reaction of bromine (or halide or other halogen) with the carbon. Optional secondary components and alkali may be added to further increase reactivity and mercury capacity.”A sorbent formed by reacting activated carbon with a halogen or halide promoter in the mercury-containing gas.

Litigation Cases New

US Latest litigation cases involving this patent.

Case NumberFiling DateTitle
4:25-cv-00154Apr 28, 2025Midwest Energy Emissions Corp. V. Evergy Kansas Central, Inc.
5:25-cv-04033Apr 2, 2025Midwest Energy Emissions Corp. V. Evergy, Inc.
4:25-cv-00046Feb 6, 2025Midwest Energy Emissions Corp. V. Evergy, Inc.

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US10926218

BIRCHTECH CORP
Application Number
US16509071
Filing Date
Jul 11, 2019
Status
Expired
Expiry Date
Aug 22, 2025
External Links
Slate, USPTO, Google Patents