carbon dioxide capture device

A Carbon Gas Captor Device by adsorption in carbon gas chemical reaction with aqueous solution, capable of reducing the emission or the percentage of carbon gas (carbon dioxide) of the atmosphere. It might be installed directly in the gases output of vehicles with internal combustion engines, or in factories' stacks, or yet in the very atmospheric air. Through pumping, this carbon gas is set in contact with an aqueous solution such as: welded lime, Calcium hydroxide, Barium hydroxide and. other solutions, comprised in an appropriate tank.

"Greenhouse effect" has been exhaustively discussed lately. It is a natural phenomenon resulting of the accumulation of gases in the atmosphere, mainly water steam and carbon dioxide, which are responsible by heat retention on the earth's surface. The gases work as a layer that keeps earth's temperature around 16 ⁰ C. Without these gases, the sun would not heat the earth enough and there would not be life on it, since the planet's average temperature would be around 17 ⁰ C and the earth's surface would be covered by ice. The phenomenon becomes more intense with the great number of pollutant gases emissions, such as, carbon dioxide (CO2), resulting of fossil fuel burning (coal, petrol and petrol-derived), rainforests and pasture; the methane (CH4), produced by the organic material decomposition; the nitrous oxide (N2O), generated by soil microorganisms' activities and Chlorofluorocarbons - compounds made up of chlorine, fluorine, and carbon- (CFCs), used in plastic packages, refrigerators, aerosols and other. These are the well known Greenhouse gases.

The International Panel on Climate Changes foresees that global temperature has risen by nearly 0,6 ⁰ C in the 20 ^th century, and may reach more than I ⁰ C up to 2030. If measures of prevention are not taken appropriately, the predictions point out that temperature will reach 4 ⁰ C up to 2090. One of the consequences of the planet's

overheating would be the oceans' level rise due to the ice - melting. If the problem gets worse, there might be a raise in sea level that may reach nearly one meter, which will cause flood along the coast and consequently make the islands disappear. The raise of air temperature also would change the wind flow characteristics and would increase the water evaporation with a consequent raise in clouds and rain. Predictions for the middle of 21 ^st Century point out the possibility of intense rain in areas that are deserts today and lack of rain in areas that are presently fertile. The CO2 global emissions resulting of fossil fuels burning have risen from 20.7 billion tons in 1990 to 24.1 billion ton in 2002, which represents a raise of 16, 4 in the period (International Energy Association). In 2002, the transport sector was the second most significant source of CO2 emissions (24%) related with energy worldwide. This rate has been increasing at 28% since 1998 as a result of the growing need for mobility of the development economies (International Energy Association). The transport segment is a source of Greenhouse gases - which increases very fast. The CO2 emissions of vehicles and transport equipment are increasing 2,5 % a year. This sector depends very much on liquid fossil fuels, which makes the control of the emissions a very hard task (UFNCCC- United Nations Framework Climate Change Convention). The vehicles are the greatest consumers of petrol in the transport sector, and the more significant source of CO2 emissions (UFNCCC). There are still many doubts concerning the emissions resulting of the rainforest clearance and other sort of change in the soil use, but it has been foreseen that 800 million to 2,4 billion ton of carbon are released globally each year (UNFCCC).

There have already been some systems which are able to withdraw the carbon gas from atmosphere, but they require too much energy and end up having a cost - benefit relation extremely high. The documents of patents PI 8100960-7, PI9500855-1,

PI0205677-1, PI0301592-0, PI0305789-5, PI0317946-0 and JP 2003326155, outline equipment and processes of carbon gas adsorption.

The PI0317946-0 addresses the air flow to a membrane system, where the carbon gas remains withdrawn and the remaining air goes back to the environment. On the other hand, the JP2003326155 uses sea water, by withdrawing carbon from the sea water's surface and placing the air in contact to this wanting carbon surface. So ₃ to keep the chemical balance, the ocean surface absorbs the carbon gas in the atmosphere. When in contact to the sea water, the CO2 will form carbonic acid which will combine with magnesium and calcium present there. This combination will not damage the marine habitat. Thus, the carbonic acid of the ocean may be separated and recovered in insoluble carbonate form. The final step is to sink this insoluble carbonate to the deepest of the ocean. In the first case, there is the inconvenience of keeping the system on the air flow. In the second case, the inconvenience remains in the withdrawn of carbon from the ocean's surface, which will generate high energy consumption. The Carbon Gas Captor Device, described on this report, does not require high energy consumptions, since it uses a simple and cheap radial compressor to suck the "polluted air" and to keep the internal pressure enough so that this "polluted air" is inflate in a waste filter and later in a tank comprising an adsorbing aqueous solution eager for carbon gas. For this report's purpose, "polluted air" includes: the gases emitted by combustions engine vehicles, the gases emitted by factories' stacks, or yet the very atmospheric air, with a carbon gas measurement superior to the one defined by the Kyoto Protocol.

The inventive act is characterized by the constructive form of the equipment, which enables its installation close to the carbon gas source and also by an easy

manufacturing of the elements comprising the equipment, thus enabling its industrial application in large scale.

Picture 1 shows a tridimension drawing of the equipment;

Picture 2 shows the equipment schematic view of the polluted air inlet (1); the inlet (13) of secondary air; the radial compressor (2) which leads the polluted air to the waste filter (3); the lid (4) for replacement of the filter elements; the conductor tube (6) of "pre clean air or the "polluted air" already filtered, to the dispenser (7); tank (8) comprising the carbon gas adsorbing element ; tank(8) tabulation (9) for gases outlet resulting of chemical reaction of the adsorbing element. Picture 3 shows detail of the dispenser (7) made up by a set of radial tubes (7a) perforated with several holes (7b).

The main carbon gas adsorption process comprises a calcium oxide (CaO) aqueous mixture or lime. Its function is to react with carbon gas (CO2) through the following chemical reactions: 1 - The calcium oxide reacts with water resulting in calcium hydroxide, through the following steps:

CaO + H ₂ O <→ Ca (OH) ₂ Ca (OH) ₂ → Ca ²⁺ +2OH-

2 - CO ₂ reaction with water, forming carbonic acid: CO ₂ + H ₂ O <→ H ₂ CO ₃

3 - The carbonic acid in water is dissociated in its respective ions:

H ₂ CO ₃ ^ H ⁺ + HCO ₃ - HCO ₃ - <→ CO ₃ ^2" + H ^"

4 - The carbon dioxide dissolved in water is then consumed by lime also dissolved in water in the following step:

Ca ²⁺ + CO ₃ ^2" <→ CaCO ₃ 5 - The global reaction is:

CaO + CO ₂ + H ₂ O <→ CaCO ₃ + H ₂ O

From this global reaction, it is shown what happens when carbonic gas (CO ₂ ) passes through a calcium oxide aqueous solution - lime (CaO).

This chemical process happens until the system reaches its saturation, which is characterized by the excess of calcium carbonate and lack of calcium hydroxide to carry out new chemical reactions, thus without reagent there's no chemical reaction and consequently, the system will not be able to withdraw carbon gas from the "polluted air". The obtained calcium carbonate (CaCO ₃ ) is solid and will remain deposited in the bottom of the tank and might be used for commercial's purpose, such as: soil PH correction (agriculture), acetylene achievement, charge for fire-extinguisher, drink gasification and other. The final product does not damage the environment.

Thus, the carbon gas captor system encompasses: An inlet tube (1) to the "polluted air", which is sucked by a radial compressor (2) and pushed in order to surpass the steal wool resistance comprised in a tank especially projected for this purpose, called waste filter (3), that might be cleaned by its lid open (4) for the element replacement purpose and with a relief valve (5) to be used in case of any rotary air impediment in the following processes. This waste filter will hold the particulate matter suspended and will adsorb other gases without carbon, by releasing the "pre clean air".

The radial compressor will impel this "pre clean air" of flowing along the dispenser (7) tube (6) by addressing up to the dispenser set (7), passing by the dispenser distributor (7a) and releasing by the dispenser's holes (7b), bubbling in the calcium

hydroxide aqueous solution, known as carbon gas captor (8), forming the "calcium carbonate".

The carbon gas air will be released then, by the gases' outlet (9).

When the calcium hydroxide aqueous solution reaches its saturation, in other words, when there is not any chemical reaction between the carbon gas and this solution, a saturation sensor (10), placed close to the reagent, will warn for the "calcium hydroxide" replacement.

The resulting "calcium carbonate" will be discharged by the waste dumping valve (11). After the discharge, the system must be fed again by the lid (12) for the reagent's replacement so that it restarts capturing the carbon gas.

It is set an atmospheric air inlet (13) between the radial compressor and the "polluted air" inlet tube in order to decrease the temperature of this "polluted air" at the environment temperature level, so that a better reaction of carbon gas with the "calcium hydroxide" may take place. That also works as a relief Valve in case of any rotary air impediment in the following processes. This air inlet will be more efficient when the system is used to capture the vehicles and factories gases emissions with temperature superior to the environment.

The whole structure of the system will be supported by the support basis (14) projected for this purpose.