Gas separation: apparatus – Magnetic separating means – And electric field separation apparatus
Reexamination Certificate
2002-03-14
2004-03-23
Chiesa, Richard L. (Department: 1724)
Gas separation: apparatus
Magnetic separating means
And electric field separation apparatus
C095S028000, C095S069000, C095S073000, C096S057000, C096S063000, C096S074000
Reexamination Certificate
active
06709490
ABSTRACT:
FIELD OF THE INVENTION
The present invention is related to the techniques for the elimination of pollutants, and more particularly, it is related to a combined system for the elimination of pollutants from gaseous effluents.
BACKGROUND OF THE INVENTION
Pollution has existed since man began to modify his environment by using tools, managing fire, and performing agriculture, thus differentiating himself from other predators. For instance, the arrival of agriculture gave place to alterations in the existing ecosystems. However, it was in a very similar way to what happened in natural phenomena.
Although such changes in the environment surrounding man are very ancient, it was until the industrial revolution when man obtained enough control over the environment as to deteriorate it. Even though such deterioration is relatively recent with respect to human history, there had to pass almost two hundred years before solutions started to be sought. In view of this, the new challenge that civilization has to face nowadays consists of knowing how to make maximum the availability of necessary goods as the cost in terms of pollution, use of natural resources and other related issues is minimized.
Other of the most affected resources, mainly in big cities, is air, which is polluted with all kind of gases and floating particles. Against what could be thought, molecules of inorganic nature are the most common pollutants in atmosphere, except for partially burnt hydrocarbons and other substances coming regularly from combustion processes. For example, in the treatment of metallic sulfur minerals, the toasting processes can be an important pollution source if there is no effort to catch the sulfur dioxide that is discharged as byproduct.
A classical example of this problem is described in the article of C. R. Hursh in 1935 in the brochure: “Local Climate of Cooper Basin of Tenessee as Modified by Removal of Vegetation”, USDA, number 774. There, it is described what happened in Copperhill, Tenn., where the products of metallic sulfur minerals toasting have altered the woods in an area of almost 220 km
2
. The woods have disappeared almost completely, although some zones with grass in a girdle covering approximately 7000 hectares still exist, thus leaving a remaining area of 28000 hectares completely without vegetation.
Less known is the damage caused by a zinc foundry in Leigh gap, Pa. It is presented in the article of M. J. Jordan in 1975 in the magazine “Ecology”, number 56, volume 78. The damage was caused by emissions of sulfur dioxide, zinc, cadmium, copper and lead. The samples of the ground, taken approximately two kilometers away from the foundry, contained more than 8% of zinc.
As it can be seen from the latter, air pollutants can also produce pollution of the ground and ecosystems due to the fact that they travel easily and rapidly. Air pollutants can be classified in different ways, considering both the emitting source and the physical and chemical features of the emissions.
It is quite difficult to characterize the pollution producing sources. There has been estimated that in the United States 60% of the air pollution comes from engine driven vehicles and 14% comes from electricity generating plants, as industry produces about 17%, the remaining 9% coming from air conditioning. The annual emission of pollutants in the United states is very meaningful since, as mentioned, engine driven vehicles contribute with about 60% of the total pollution, from which almost all is carbon monoxide, two thirds of hydrocarbons, one half of nitrogenous oxide and little fractions of other compounds.
The pollution due to combustion engine driven vehicles is a much bigger problem in big cities, and even more in the largest such as Mexico City. In big cities the extent of urban areas and the intense economic and social life forces people to travel great distances in order to perform their ordinary activities.
It is estimated that in Mexico City, vehicle emissions represent about 76% from the total pollutants emitted to the atmosphere; private vehicles emit more than half the pollutants of vehicular origin, and when using gasoline, they also produce lead oxides, sulfur and suspended particles.
Nevertheless, it is necessary to consider that pollutants come from fixed sources as well as from mobile sources. In developing countries it has been found that environmental pollution comes mainly from industries that throw their wastes illegally during the night, i.e., pollution comes from fixed sources.
On the other hand, in its simplest form, control of air pollution needs basic knowledge for establishing adequate criteria in order to maintain the freshness of air; ability to relate air quality to emission levels; establishment of emission limits or other control standards; means for measuring emissions and air quality and availability of practical techniques for reducing the emissions that pollute it.
In regard to the practical techniques for reducing emanations, even though it has been given attention to process changes that reduce polluting emissions, a great confidence has been given also to physical processes for eliminating such pollutants therefrom.
Within the existing techniques, a distinction is made between those developed for appliance on mobile sources directly and those developed to be used in fixed sources. It is worth mentioning that most of them have focussed on the treatment and control of emissions coming from fixed sources. This is probably due to the easiness of installation, operation and maintenance and to the pressure exerted by governments over industries, thus forcing them to install apparatus that enable them to comply with the increasingly strict rules in regard to the pollutants emitted to the atmosphere.
The apparatus used to clean the air from particles coming from fixed sources are based basically on aerodynamic catch, such as inertial impact, direct interception and diffusion. However, some apparatus use electrical and thermal forces, chemical reactions, and apply principles such as absorption, adsorption, condensation, etc.
Filtration is one of the most used methods, in which various types of filters are incorporated in direct interception processes as well as in diffusion processes, in a way that there can be achieved very high efficiencies not only with big particles but with the small ones. The use of these principles has resulted in the development of various technologies. For instance, Mexican Patent No. 131020 is related to an air purifying apparatus. It comprises at least one particle-filtering module in one of its walls and an activated carbon filter module, wherein the particle-filtering module comprises a filter for fine particles and one for bulky particles.
Another example is the portable air purifier of Mexican Patent Number 188350 which comprises one chamber with an air intake and an air outlet, as well as a filtration means provided inside the chamber between the air intake and the air outlet. They are assembled in such a way that when air crosses through the chamber, the particles are retained due to the filtration means.
Among the possible variations there can be found bag filters, which are capable of managing particles having diameters of less than 1 micron. However, they show the disadvantage of having a maximum operating temperature of 500° F. and generating pressure drops higher than 4 in H2O, although they can achieve efficiencies around 99% and need little space for its operation. An additional inconvenient of these filters is the great sensitivity of the bags to humidity, filtration rates and temperature.
Obviously, there can be used different types of filters to achieve a better separation of the pollutants, as described in Mexican Patent Application number 9101571. The method is based on a filtration system comprising pre-filters, absolute filters and activated carbon filters that purify and sterilize polluted air, which is forced to pass through the same by means of one or more fans; thus achieving a retention efficiency of the filters of about 95%.
Th
Chiesa Richard L.
Rothwell Figg Ernst & Manbeck
LandOfFree
Combined system for removing contaminants from gas effluents does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Combined system for removing contaminants from gas effluents, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Combined system for removing contaminants from gas effluents will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3240693