United States Patent Application: 0030206843
There is, actually, a lot "going on" in the US EPA-sponsored technical development for capturing and sequestering Mercury in the emissions of Coal-fired power plants.
And, there will be a lot "going on" in our presentation, herein, of the issue.
First of all, whether we like it or not, current and pending laws do or will require that Coal-fired power generating stations have or install some form of Mercury emission control within the next decade.
That, even though our generation of electricity from Coal, as large as that enterprise is, as explained in:
"Fundamentals of mercury transformations in coal combustion flue gas - " by Balaji Krishnakumar;
"'Fundamentals of mercury transformations in coal combustion flue gas - A theoretical and modeling study'; Balaji Krishnakumar; 2008; University of Connecticut. Paper AAI3334959";
produces less than half, admittedly only slightly less than half, of the Mercury emissions of US industry.
The technology for capturing Mercury in flue gases does exist; and, in some places has been installed.
There are, in fact, a couple of different competing technologies, with, as expected, trade-offs in costs and performance between them.
A knee-jerk reaction to the issue has been a seeming, and short-sighted, push to convert Coal-fired boilers to natural gas.
The flush of news reports recently concerning the Shale Gas rush has everyone thinking that gas is an abundant resource.
In terms of actual energy content, relative to Coal, it is not.
And, in fact, it is not nearly as abundant, in terms of the actual amount of it, as everyone has been led to think. As we may document in future reports, even with the new Shale Gas reserves that have been more recently rediscovered - again, we've known about it for quite awhile, we're only going after it now since it has become less expensive to undertake environmentally hazardous hydro-fracking operations - there are only a few decades worth of it available; less if we start using it wholesale to generate electricity.
We have hundreds of years' worth of Coal still in the ground.
Further, the relative, to Coal, energy content of natural gas, on a volume-to-volume basis, is so low that we would have to burn a lot, really a lot, of it, at great expense, in order to generate the same amount of electricity from it as we do from Coal.
And, once power plants are converted, and more gas is being used, and it grows scarcer, the price for natural gas will only go up and up.
But, even right now, with the seeming abundance of natural gas and it's current seemingly-reasonable cost, the electricity generated from that gas in a boiler that has been converted from Coal, with the capital expense that, with attendant infrastructure changes, requires, will, as can be learned from accompanying tables and charts in:
The Trouble With Being Coal - Public Power Magazine - Public Power Media; Public Power Magazine of the American Public Power Association; January-February, 2011; Edward Cichanowicz; "Given this challenge, (of meeting the Clean Air Transport Rule (CATR) and the Utility Boiler MACT (maximum achievable control technology) rule) some owners may ask whether it is worth the cost and risk to invest heavily in environmental controls, and continue to use coal. Or, should they swap the relative certainty of coal prices for the market-driven uncertainty of natural gas to avoid high capital expenses? Would a switch to natural gas be cheaper and better for the operator? A boiler designed for coal can fire natural gas, but would require capital for new burners or gas injectors, and possibly rebuilding flue gas fans. Changes to high-pressure steam tubes might be required, depending on how heat release within the boiler is affected. But perhaps most importantly, the thermal efficiency of the fuel used to generate power would decrease significantly, increasing fuel needs. Consequently, a boiler designed for coal operating at 33 percent thermal efficiency, after switching to natural gas, would likely experience lower thermal efficiency, perhaps to 28 percent. A greater amount of fuel must be purchased—and in this case at a premium price—to generate the same power. But the biggest uncertainty could be availability of natural gas. Some power plants may be located at sites equipped with gas access; others may be within 25 miles of a relatively large (36-inch) gas main supply line. Yet other generating units will be hundreds of miles from a large gas source. With pipeline installation cost of $300,000 to $1 million per mile, developing access to gas could be the largest capital expense.(An accompanying table) shows the switch to gas would require a capital cost of $42 million, and a total operating cost of $86.7 million. The higher operating cost is mostly for higher fuel charges, and reflects both the additional fuel cost beyond coal-firing, and the fixed payment for boiler capital and the pipeline. (A) gas switch could save over several hundred million dollars in capital, but would require an additional $25 million to $35 million per year in operating cost. (A) switch to gas will save capital, but in exchange for long-term higher operating costs. The near-term savings are attractive in the present economy, but affordable long-term power is in everybody’s interest."
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virtually triple the costs of electricity to consumers.
And, that is at the current seeming-abundance and seeming-low cost of natural gas.
Since "affordable long-term power is in everybody’s interest", what happens in a decade or two, when the increased demand for natural gas has caused it to become scarce, and, via laws of supply and demand, even more, much more, expensive, especially on a cost-per-Btu basis?
Doesn't it seem far, far better to, now, make the investments in Coal that can be amortized over long periods of time, with ever-decreasing costs, as opposed to making investments in conversions to natural gas, with the inevitably ever-increasing costs?
Toward that end, we submit herein one way to go about the control of Mercury emissions in Coal-fired power plants that seems, since they paid to have it invented, to not only satisfy the requirements of the United States Environmental Protection Agency; but, which also provides a way in which some return on the investment in Mercury capture can be achieved.
Comment, with additional links and excerpts, follows and is inserted within excerpts from the initial link to:
"United States Patent Application 20030206843 - Methods and Compositions to Sequester Combustion-Gas Mercury in Fly Ash and Concrete
Date: November, 2003
Inventor: Sidney G. Nelson, Jr., Ohio
The United States Government may own certain rights to present invention pursuant to U.S. Environmental Protection Agency Contract No. 68-D-01-075 and National Science Foundation Award No. DMI-0232735, to Sorbent Technologies Corporation.
(Note: Inventor Sidney Nelson presumably is, or was, employed by "Sorbent Technologies Corporation". As can be learned via:
http://www.netl.doe.gov/
Lynn Brickett, Project Officer; Sorbent Technologies Corporation; Sid Nelson Jr., Project Director";
the technology disclosed herein was proven in "large scale tests" financed and supervised by the USDOE.
However, "Sorbent Technologies" no longer exists as an independent company. As can be learned via:
Sorbent Technologies Corporation: Private Company Information - Businessweek; "As of July 31, 2008, Sorbent Technologies Corporation was acquired by Albemarle Corp. Sorbent Technologies Corporation provides sorbents, equipment, and services for the control of mercury emissions from utility and power plant boilers. The company ... is based in Twinsburg, Ohio";
it has, since the work performed herein by Sid Nelson, been acquired by Albemarle Corporation, which might not be a bad thing. We've actually mentioned and cited Albemarle in one or two previous reports, which we can't at this time locate; but, as can be learned via:
Home | Albemarle: "Albemarle is a leading specialty chemical company providing innovative chemistry solutions to customers in over 100 countries around the world"; and:
Albemarle Corporation - Wikipedia, the free encyclopedia: "Albemarle Corporation ... is a chemical company with corporate headquarters in Baton Rouge, Louisiana. It is a specialty chemical manufacturing enterprise (and) one of the world's largest producers of hydro processing catalysts (HPC) and fluidized catalytic cracking (FCC) catalysts used in the petroleum refining industry";
they are an operation of some significant substance who serve, basically, the petroleum industry, which has Mercury emission issues of it's own, and who likely have the financial heft and staff support to make this Mercury control technology a commercially-viable and available option.)
Abstract: A method for removing mercury from a combustion gas in an exhaust gas system has the steps of providing a mercury sorbent; injecting the mercury sorbent into a stream of the mercury-containing combustion gas to enable mercury to adsorb onto the sorbent; and collecting and removing the sorbent from the combustion gas stream. The mercury sorbent is prepared by treating a carbonaceous substrate with an ozone-containing gas to increase the ability of the substrate to adsorb mercury. Concrete compositions with fly ash containing the mercury sorbents will have reduced interference with air-entraining-admixtures.
(The above is actually succinct and to-the-point information, although it leads into other technical areas. The specified "treating a carbonaceous substrate with an ozone-containing gas" actually refers to the treatment of Coal Fly Ash which contains some residual Carbon, a phenomena we have previously documented, and which is now a larger problem due to other emission controls, with Ozone, to "passivate" or oxidize the residual Carbon, especially so that the Fly Ash doesn't interfere with air entrainment, a process used in making high-performance Concrete from Portland-type Cement.
We'll have more to report in the future about the treatment of Fly Ash with Ozone, since some new developments have been made in the technology by Rhode Island's Brown University.
That is as opposed to "Carbon Burn Out" processes as applied to Coal Ash, so that it can be better used as an aggregate in Concrete without interfering with "air entrainment", as represented in our report of:
a process which contributes to the development of valuable properties in Portland Cement Concrete utilizing Coal ash as an aggregate or filler.
Carbon Burn Out wouldn't be needed for Fly Ash generated through the technology of our subject, "United States Patent Application 20030206843", although it would still be beneficial for Fly Ash generated by Coal power plants not so equipped and Fly Ash recovered for use from older Fly Ash impoundments and dumps, unless the Fly Ash, instead of being used as Concrete aggregate, was to be used, as in:
West Virginia Coal Association | Pittsburgh Converts Coal Ash and Flue Gas into Cement | Research & Development; concerning: "United States Patent 5,766,339 - Producing Cement from a Flue Gas Desulfurization Waste; 1998; Assignee: Dravo Lime Company, Pittsburgh; Abstract: Cement is produced by forming a moist mixture of a flue gas desulfurization process waste product containing 80-95 percent by weight calcium sulfite hemihydrate and 5-20 percent by weight calcium sulfate hemihydrate, aluminum, iron, silica and carbon, agglomerating the moist mixture while drying the same to form a feedstock, and calcining the dry agglomerated feedstock in a rotary kiln (and) wherein said source of aluminum and iron comprises fly ash";
to make, as "US Patent 5,766,339" specifies in it's full Disclosure, "cement clinker".
Nor would Carbon Burn Out be needed to, then, as in:
West Virginia Coal Association | Canada Coal Ash Cement | Research & Development; concerning: "United States Patent 5,837,052 - Process for Producing Cement Clinker Containing Coal Ash; 1998; Assignee: Lafarge Canada, Inc.; Abstract: Contaminated coal ash, for example flyash contaminated with carbon is introduced to hot clinker in a cooler downstream of a cement kiln";
add more Fly Ash to that "cement clinker" to make the final, powdered Portland Cement product.
However, Fly Ash produced by the process of our subject herein, "United States Patent Application 20030206843", would be carrying a burden of Mercury, extracted from the Coal power plant exhaust, which could be liberated by the above, and similar, processes of "United States Patent 5,766,339" and "United States Patent 5,837,052".
But, as can be learned via:
EPA finalizes rules cutting mercury from cement | Reuters; "EPA Finalizes Rules Cutting Mercury From Cement; 2010; U.S. environmental regulators finalized rules on Monday aimed at cutting mercury emissions and other pollution from Portland cement manufacturing";
the manufacture of Portland Cement, since it, too, entails the high-temperature treatment of geologic raw materials, also has it's own Mercury emission issues.
And, it might, in the long run, be more economical to consolidate Mercury control, and share it's associated costs between power producers and Cement makers, at Cement manufacturing facilities which could switch their raw material stream into one consisting in large part, or even, as is possible, entirely of Coal Ash and other, as especially in the above-cited "United States Patent 5,766,339 - Producing Cement from a Flue Gas Desulfurization Waste", Coal Utilization Byproducts.
Again, though, with apologies for the lengthy interruption, such concerns would not really apply to the Mercury-laden product of our subject herein, "United States Patent Application 20030206843 - Methods and Compositions to Sequester Combustion-Gas Mercury in Fly Ash and Concrete", since the Ash is intended only for use as an aggregate, wherein the burden of Mercury wouldn't be heated to the point of volatization, but would, instead, be "sequestered" in the Concrete made from the Mercury-laden Fly Ash, used only as an aggregate, well unto the end of time.)
Claims: A method for removing mercury and mercury-containing compounds from a combustion gas in an exhaust gas system, comprising the steps of: providing a mercury sorbent that has been prepared by treating a carbonaceous substrate with an effective amount of an ozone-containing gas for a time sufficient to increase the ability of the carbonaceous substrate to adsorb mercury and to reduce the degree of possible interference of the sorbent with air-entraining-admixtures used with the substrates as a component of a concrete composition; injecting the mercury sorbent into a stream of the mercury-containing combustion gas for a sufficient time to allow an effective amount of the mercury and mercury-containing compounds in the combustion gas to adsorb onto the mercury sorbent; and collecting and removing the mercury sorbent from the combustion gas stream.
The method ... wherein: the carbonaceous substrate comprises activated carbon.
(Don't be misled by the terminology. The "carbonaceous substrate" is Carbon-containing Fly Ash; and, the "carbon" in the Ash is "activated" by treatment with Ozone. However, and the full Disclosure doesn't really make it too clear, some supposition and extrapolation is required, and, additional activated Carbon, from an independent source, might, likely will, have to be added to supplement the Carbon in the Ash.)
The method ... wherein: the carbonaceous substrate or mercury sorbent is reduced to a particle size distribution fluidizable in the combustion gas stream.
A process for manufacturing a mercury sorbent, comprising: providing a carbonaceous substrate; providing a ozone-containing gas; and contacting the carbonaceous substrate with the ozone-containing gas for a time sufficient to increase the mercury adsorbing ability of the carbonaceous substrate and to reduce the degree of interference of the substrate with air-entraining-admixtures used with the sorbent as a component of a concrete composition.
The process ... wherein: the carbonaceous substrate is activated carbon (and) further comprising the step of: reducing the particle size distribution of the carbonaceous substrate or mercury sorbent to a distribution that is fluidizable in the ductwork of a combustion gas stream.
A process in which ozone is used to pacify the surface of a carbon source material extrinsic to ash comprising applying ozone to said carbon source material extrinsic to ash to produce a product which reduces the undesirable affect on air entrainment when said carbon source material is incorporated into concrete.
The process ... in which the carbon source material is treated separately with ozone and then added to the ash stream.
(Note that, as in our earlier comments, some additional "carbon source material" might have to be "added to the" activated Coal Ash.)
A process comprising oxidizing activated carbon-based sorbents which are used to capture metal vapors, said oxidizing reducing the undesirable affect on air entrainment when said activated carbon-based sorbents are to be incorporated into ash and the ash subsequently used in concrete.
The process ... where the metal vapor is either oxidized or elemental mercury.
The process ... in which the oxidant is ozone.
The process ... in which the activated carbon is treated prior to its use as a mercury sorbent, so that the final ash is not degraded in its concrete performance.
A process of surface oxidation used to pacify the surface of a carbon containing source material extrinsic to carbon containing ash comprising the step of surface oxidation of said carbon containing source material to prepare a material useful for incorporation into concrete.
(Again, the "carbon containing source material" can be in addition "to carbon containing ash"; and, the differentiation and potentials for synergy should be made more apparent in our pending reports concerning the closely-related work, which we made note of above, at Brown University.)
The process ... wherein the surface oxidation is performed with ozone.
The process ... wherein the oxidation is performed with a member selected from the group of air, oxygen, nitric acid, chromic acid, persulfate, permanganate, and hydrogen peroxide.
(Note, other agents of oxidation, as above, aside from Ozone, can be used. However, review of related literature strongly indicates that Ozone is the most preferable, perhaps most economic, choice.)
A concrete composition comprising concrete and an ozone treated carbon source material extrinsic to ash wherein the undesirable affect on air entrainment is reduced.
(Again, some additional "ozone treated carbon" will have to be added to the Ash.)
Background and Field: This invention relates to the injection of carbon sorbent materials into the combustion gas streams of coal-fired power plants to remove mercury and to the use in concretes of the mixture of fly ash and sorbents recovered from the combustion-gas particulate-collector.
After a thorough investigation of the prior art on mercury removal from power-plant gas streams, the U.S. Environmental Protection Agency (EPA) concluded in the Executive Summary to its 1998 Utility Hazardous Air Pollutants (HAPs) Report to Congress that: 'Regarding potential methods for reducing mercury emissions, the EPA has not identified any demonstrated add-on control technologies currently in use in the U.S. that effectively remove mercury from utility emissions'.
(Thus, currently-proposed, overly expensive and essentially non-productive, Mercury control technologies currently proposed for mandated installation likely won't get the job done in any case.)
Contamination of the fly ash by the mercury sorbent further complicates the problem of mercury control at coal-fired power plants. Almost 20% of U.S. power-plant fly ash is beneficially used as a cement substitute in concrete. Power plants that can sell their fly ash not only receive income for their waste product, but save even more in avoided landfill costs. This great industrial recycling success story, however, is now threatened by PAC (powdered activated carbon) injection for mercury control.
PAC duct-injection trials at We Energy/Wisconsin Electric's Pleasant Prairie power plant in Wisconsin were the first large-scale mercury sorbent tests at a representative, ESP-equipped U.S. power plant. The Pleasant Prairie plant burns a subbituminous coal and, at the time, sold all of its fly ash as a cement replacement in concretes. Mercury-removal performance in the trials was modest, with over 40% removal when a Norit Darco FGD.RTM. PAC was injected at 1 lb/MMacf, but leveling off at about 70% removal when the injection rate was greater than 10 lb/MMacf. However, it was also discovered that the suitability of their fly ash in concretes became severely compromised with PAC injection.
Even at the lowest injection levels tested, when the PAC became incorporated in the plant's fly ash in the ESP, the fly ash failed the required specification tests for concrete use. The problem is that the PAC that was designed to be such an efficient adsorbent material for mercury is, by its nature, also an excellent adsorbent for the organic air-entraining-admixtures (AEAs) added to concretes to produce and stabilize fine air bubbles in the matrix, which provides workability, strength, and freeze/thaw capabilities. The economic implications of this PAC interference with AEAs could be huge. At Pleasant Prairie, for example, the loss in fly ash revenues and added land-disposal costs would be a few times greater than the total mercury-control costs.
Fly ash usually already contains some unburned carbon particles from incomplete fuel combustion. These, too, interfere with AEAs. Because over two-thirds of concrete in the U.S. is air-entrained, a number of methods have been developed to decrease the foam indexes of carbon-containing fly ashes.
If power plants are to add highly-adsorbent PACs to their flue gas streams for mercury control, methods are needed to reduce the sorbent impact on AEA in concrete.
Accordingly, it is an object of the present invention to provide a sorbent material that may be injected into a hot mercury-containing flue gas, so that a significant portion of the mercury is sequestered onto the sorbent and removed from the flue gas with its fly ash.
In addition, it is an object of the present invention to provide a sorbent material that has a reduced interference with air-entraining-admixtures when a fly ash incorporating the saturated sorbents is used in concretes, sequestering the power-plant mercury from the environment."
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That's a long dissertation; but, our final excerpted passage sums it up nicely.
We can used Coal Ash, treated with Ozone and perhaps supplemented with an additional Carbon-based "sorbent", to absorb and remove Mercury from Coal-fired power plant flue gas.
And, we can do so in a way that limits the effect of that Carbon-containing, Mercury-laden Ash on Air Entraining Agents used in the making of freeze-thaw resistant structural Concrete from Portland Cement, wherein the Coal Ash is used as an aggregate filler.
Keep in mind that the "power-plant mercury" thus productively sequestered "from the environment", in the structures made from Fly Ash-supplemented Portland cement concrete, would remain so sequestered virtually forever. Bridges and buildings made by the Romans more than two thousand years ago out of closely-similar Concrete, supplemented with volcanic Ash as an aggregate and reactive pozzolan, just as Coal Ash can be used, are not only still standing, sound and solid, but, some are still in use.
Although, as we will in future reports document, there are other potentially productive options, if we are going to be compelled to control and collect the Mercury in the emissions from our Coal-fired power plants, this might be a one good way to go about it.
It helps to preserve the utility of Coal Ash as an aggregate for concrete, without entailing the costs of Carbon Burn Out, since this technology helps, in addition to sequestering Mercury, to reduce the negative effects of Coal Ash Carbon on the "air entraining admixtures" used in Concrete; which commercial use could help to finance the costs of the Mercury control while permanently sequestering an objectionable material the forces allied against Coal have used as a spearhead against us.
Such innovative and productive options for Coal Country, as herein sponsored and promulgated by the vilified United States Environmental Protection Agency, can't get used, however, unless they get known.
When, do you suppose, that might, finally, happen?