Chemistry of inorganic compounds – Modifying or removing component of normally gaseous mixture – Carbon dioxide or hydrogen sulfide component
Reexamination Certificate
1999-06-04
2001-02-13
Griffin, Steven P. (Department: 1754)
Chemistry of inorganic compounds
Modifying or removing component of normally gaseous mixture
Carbon dioxide or hydrogen sulfide component
C423S226000, C423S242100, C423S243010, C423S243080, C423S430000, C423S554000, C423S555000
Reexamination Certificate
active
06187277
ABSTRACT:
TECHNICAL FIELD
This invention relates to reduction of sulfur and CO
2
emissions from the stack gases from fossil fuel fired boilers.
BACKGROUND OF THE INVENTION
The reliance on fossil fuels, particularly coal, for the foreseeable future by the power utility and industrial sections (e.g. iron, steel and cement making) of our economy and the US′ commitment to a clean environment will require vigilant waste management of SO
2
, CO
2
and NO
x
.
Sulfur dioxide is a distinctly ubiquitous gas pollutant in that it is of consequence as a toxic gas in industrial gases as well as the general atmosphere and therefore of public health importance. While sulfur dioxide discharge occurs as consequence of the combustion process primarily from the burning of sulfur-containing fossil fuels, petroleum refining, manufacturing of sulfuric acid and smelting of sulfur containing ores also contribute to the sulfur dioxide atmospheric inventory. The major origin of sulfur dioxide is from sulfur bearing coals burned in the process of producing electrical energy. The magnitude of this pollution source can be realized as over 900 million tons of coal was consumed in 1997 (Electric Power Monthly, October 1998, US Energy Information Administration, Table 14). Sulfur dioxide's impact ecologically is seen as the cause of acid rain. As such, it is responsible for damage to agricultural crops and the despoiling of natural lakes and the wildlife dependent on such resources throughout the world, notably in the US and Canada.
Carbon dioxide, until recently, was a gas that had been viewed to be at most 1) a benign consequence of the combustion of carbon bearing compounds, primarily coal and 2) even a desirable end product of the incinerator control of undesirable organic and volatile compound emissions. This view has been radically altered within the last decade as a result of long range studies of the origins of global warming which appears to be a consequence of the growing volume of greenhouse gases, primarily carbon dioxide, being generated worldwide. Changes in the permafrost are postulated as proof of this change. In the May 1, 1998 Report of the Council of Economic Advisors, Dr. Janet Yeltin, its chairperson addressed the seriousness of this problem. Dr. Yeltin projected that the recommendations of the Kyoto Protocols on international commitments to reduce present day carbon dioxide emissions generated by fossil fuels combustion (particularly coal) by the US to 1990 levels would cost between $70-110/household. As this cost would be borne by 98 million households, the financial outlay can be seen as enormous. Translating this projection into meaningful data: 773 million tons of coal were consumed for electrical energy generation in 1990 and 900 million tons in 1997. Two Hundred pounds per hour of CO
2
are generated from every 90 lbs. of coal consumed to create 1 million BTU of energy. This is approximately a 14% reduction in emission output. It is these considerations which make desirable a tandem scrubber design to reduce not only sulfur dioxide levels to 1.2 lbs./million BTU (520 nanograms/J heat input) or less as well as the carbon dioxide levels to those found at the 1990 level of coal consumption.
Another problem faced by many states with high sulfur coal, such as Illinois, is that they have limited commercial outlets for their coal. The mandate to remove both sulfur dioxide and carbon dioxide from the emission stream creates an opportunity for this technology and methodology to create new jobs in both the coal and construction industry.
Although DMSO has been widely used in biomedical applications, its use in clean air technologies is novel and, as such, DSMO has not been seriously considered as a factor in the removal of sulfur dioxide in environmental research involving the prevention and control of sulfur dioxide emissions in fossil fuel combustion. Flue gas emission research dealing with the removal of carbon values subsequent to the complete removal of sulfur dioxide (with DMSO or otherwise) is not widely reported in the literature and is certainly not a common place practice in the utility or manufacturing industries.
SUMMARY OF THE INVENTION
I have found that combustion gases from coal fired boilers containing both sulfur oxide and carbon oxides can be remedied using dimethyl sulfoxide, hereafter DMSO, and calcium ions obtained from cement waste materials and other common raw materials. I further have found that by controlling the pH of an aqueous DMSO solution, sulfur values and carbon values can be sequentially removed while preserving the DMSO for additional use. An important difference between the inventive process and prior art uses of DMSO is the inventive process makes use of chemical separation requiring the presence of ions for chemical reaction. Accordingly, aqueous solutions of DMSO are employed to provide ions for the chemical reactions with the sulfur and carbon dioxide values, preferably as calcium salts with the calcium ions being provided by commonly available materials, such as waste cement or naturally occurring limestone.
REFERENCES:
patent: 1363992 (1920-12-01), Payne
patent: 3538681 (1970-11-01), Cantrell et al.
patent: 3733781 (1973-05-01), Bellisio et al.
patent: 4100257 (1978-07-01), Sartori et al.
patent: 4157379 (1979-06-01), Arika et al.
patent: 4528002 (1985-07-01), Linde
Kohl et al.Gas Purification4th Ed. Gulf Publishing Co. Houston TX; ISBN 0-87201-314-6, pp. 307-320, 1985.
Emrich & -Dithmar
Griffin Steven P.
Vanoy Timothy C
LandOfFree
Method for purifying gases does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for purifying gases, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for purifying gases will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2589562