| WO2007063535A2 | 2007-06-07 | |||
| WO2008018928A2 | 2008-02-14 |
| EP0128698A1 | 1984-12-19 | |||
| CA1181927A | 1985-02-05 | |||
| EP2578298A1 | 2013-04-10 | |||
| CN102423594A | 2012-04-25 | |||
| EP2305365A2 | 2011-04-06 | |||
| EP1716909A2 | 2006-11-02 | |||
| DE19534558C1 | 1996-11-07 | |||
| DE102007043331A1 | 2009-02-19 | |||
| US4544542A | 1985-10-01 |
| CLAIMS 1. A process for minimizing/eliminating the emission of C02 and/or S02 emerging from the combustion of the coal characterized in that the carbon dioxide (C02) and/or sulfur dioxide (S02) emitted from the flue is/are guided and reacted with the caustic soda (NaOH) and/or limestone (CaC03) by a method of spraying on a fluidized bed. 2. A process according to Claim 1 characterized in that by means of a method for guiding the carbon dioxide (C02) emitted with the flue gas and spraying on a fluidized bed, the C02 emission is eliminated and the soda (NaHCO3) is formed as a result of the reaction of the carbon dioxide (C02) with the caustic soda (NaOH) (NaOH + CO2 + H2O NaHC03 + H20). 3. A process according to Claim 1 characterized in that the mixture of water and soda thus formed (NaHCO3 + H2O) is dried and the soda (NaHCO3) is utilized. 4. A process according to Claim 1 characterized in that it comprises the process steps of - reducing the SO2 emission by way of the treatment of the flue gas with the limestone (CaCO3) (CaCO3 + SO2 Ca2SO4), - performing a method for guiding the flue gas and spraying on a fluidized bed whereby the CO2 emission is eliminated and the soda (NaHCO3) is formed as a result of the reaction of the carbon dioxide (CO2) contained by the flue gas with the caustic soda (NaOH) (NaOH + CO2 + H2O NaHCO3 + H2O), - completely terminating the SO2 emission as result of the reaction of the residual SO2, which remains after the limestone (CaCO3) and caustic soda (NaOH) treatments, again with caustic soda (NaOH) (NaOH + SO2 Na2SO4; NaOH + SO2 NaHSO4) 5. A process according to Claim 4 characterized in that the limestone (CaCO3) is used at an amount less than 2% by weight. |
PROCESS FOR THE MINIMIZATION/ELIMINATION OF S0 2 AND C0 2 EMISSION
EMERGING FROM THE COMBUSTION OF COAL
Technical Field
The invention relates to the emission of gases formed by the combustion of coal.
The invention relates in particular to a process for minimizing/eliminating the C02 and S02 emission emerging from the combustion of coal.
State of the Art
Today, the coal is commonly used for the purpose of residential heating. The lignite coals generally used have a high content of sulfur. S02 emission released into the atmosphere along with the flue gases as a result of combustion causes substantial damages to the human health and natural environment. In our country, the coals allocated to the residential sector are perceived as the grain coals with appropriate calorific value, which are washed and sieved, and generally no reduction is performed in the sulfur content of the original coal.
The most practical solution for the reduction of SO2 emissions of this type of coal, which is employed for the residential heating and which is not problematic in terms of combustion, is the mixing of the lime into the coal. In this study, the combustion and emission properties of the burners were experimentally examined for the case of no lime addition as well as for the case of application of numerous methods of lime addition, in association with the coals of various types and properties for use in the stoves and boilers employed in the residential heating, and the effects of the lime addition on the burning and emission behavior of the combustion system were investigated. In the boiler tests, a reduction of about 30% was provided in SO2 emission, while the combustion was impaired, the combustion efficiency was reduced by 7% on the average and the thermal efficiency of the boiler was reduced by 4%. In the stove tests, the addition of lime into the coal provided a reduction of 50% in S0 2 emission without leading to any impairment in the combustion efficiency.
The side and environmental impacts of coal are listed below:
■ In America, 2.800 out of 24.000 individuals resident in the vicinity of the factories that utilize coal as the fuel contracted the lung cancer within 1 year.
• The desulfurization of the flue gas, which contains the fly ash, bottom ash, mercury, thorium, arsenic and other heavy metals, generates millions of waste such as the sludge.
• Acid rain is formed due to the coals with high sulfur content and it causes mixing between the drinking water and the groundwater.
■ The coal causes the pollution in the soil and the water courses as well as the spills of the fly ash resulting in destructive effect on the houses.
• It affects the utility water in the running rivers, hence the other soils.
• It causes the nuisance of dust particles floating in the air.
• The settling on the tunnels damages the infrastructure.
• The factories running on coal with inefficient fly ash reduction methods result in the exposure to the background radiation as the most commonly encountered situation for the humans.
• It causes the change in the global climate due to the CO2 gas it emits. The humans are the most significant contributors to the increased CO2 content in the air.
Today, there are many approaches towards the use of the retained CO2 in a rational manner. One of these is the production of the microalgae and the utilization of this biomass for numerous energy-related purposes. Such a promising solution requires a clearly strong competence in biology and bioengineering.
According to the state of the art, the invention no. EP2227312B1 entitled "Method and device for reprocessing CO2-containing exhaust gases" relates to a method for reprocessing the CO 2 -containing exhaust gases in a multistage reduction process. The CO 2 -containing exhaust gas is conducted in the counter stream to a solid mass stream of inert bulk material and organic material that can be thermally decomposed through a plurality of zones into a pressure equalization region and is thereby converted into pyrolysis gases. In the flow direction of the solid mass stream in a fuel gas production stage at 250-700°C, the organic matter is thermally decomposed under reducing conditions into short-chained hydrocarbons, hydrogen and carbon monoxide to produce coke and residue.
Further, the invention no. JP 9980057415 entitled "Method and system for processing the flue gas" relates to a method for subjecting the flue gases to treatment, said method including a step of heat recovery from the flue gas by means of a heat exchanger and also the heat recovery aiming to cool down the flue gas as well as a subsequent absorption step that involves bringing the flue gas into the gas- liquid contact with an absorbent-fluid from the absorption towers, thereby enabling the absorbent-fluid to absorb and eliminate SO2 present at least in the flue gas, said method being characterized in that there is conceived, prior to the step of heat recovery for instance, also a step of adding a powder, which is collectable at the stage of absorption, for example, for the purpose of spraying the coal ash into the flue gas. By means of the possibilities provided by the flue gas processing method according to this invention, it becomes easy to provide a counter measure for SO3 that is present in the flue gas, without resorting to the spraying of ammonia, it becomes also possible to treat the flue gas even better, and besides, there is no drawback causing the sprayed matter to remain within the flue gas.
Object of the Invention
In order to eliminate the disadvantages in the state of the art, an object of the invention is to minimize/eliminate the C0 2 and SO2 emission emerging from the combustion of coal.
Another object of the invention is to provide the soda generated as a significant input for the glass industry.
In order to achieve the aforesaid objects, the invention is a process for minimizing/eliminating the C0 2 and S0 2 emission emerging from the combustion of coal characterized in that it comprises the process steps of - reducing the S0 2 emission by way of the treatment of the flue gas with the limestone (CaC0 3 )
(CaC0 3 + S0 2 Ca 2 S0 4 ),
- performing a method for guiding the flue gas and spraying on a fluidized bed whereby the C0 2 emission is eliminated and the soda (NaHC0 3 ) is formed as a result of the reaction of the carbon dioxide (C0 2 ) contained by the flue gas with the caustic soda (NaOH)
(NaOH + .CO2 + H 2 0 NaHC0 3 + H 2 O),
- completely terminating the S0 2 emission as result of the reaction of the residual S0 2 , which remains after the limestone (CaC0 3 ) and caustic soda (NaOH) treatments, again with caustic soda (NaOH)
(NaOH + SO 2 Na 2 SO 4 ;
NaOH + SO 2 NaHSO 4 )
Detailed Description of the Invention
The invention is a process for minimizing/eliminating the carbon dioxide (CO 2 ) and sulfur dioxide (SO 2 ) emission emerging from the combustion of coal. The process according to the invention preferably comprises the process steps for the elimination of the emission of first SO 2 , then CO 2 and finally the residual SO 2 .
1. SO 2 Emission: In case the limestone (CaCO 3 ) is used at calculated values along with the coal during the combustion in the stove, the amount of released SO 2 is reduced considerably.
The reaction equation is as follows:
CaCO 3 + SO 2 Ca 2 SO 4
Sulfur dioxide (SO 2 ) is a colorless, odorous reactive gas that forms during the combustion of the sulfur-containing fuels such as the coal and fuel-oil and as a result of the metal melting processes and the other industrial processes. Its primary sources are the thermal power plants and the industrial boilers. The highest SO 2 concentrations are generally found in the vicinity of the big scale industrial sources. For example, the limestone at a ratio of 1/15 - 1/20 by weight (depending on the percentage of sulfur) is used as an additive for Soma coal. (For example, this should not exceed 2% according to Turkish Standards, whereas the value is 0,9% for Europe and around 1 ,2% for Soma.)
2. C0 2 Emission: By means of a method for guiding the carbon dioxide (C0 2 ) emitted with the flue gas and spraying on a fluidized bed, the C0 2 emission is eliminated and the soda (NaHC0 3 ) is formed as a result of the reaction of the carbon dioxide (C0 2 ) with the caustic soda (NaOH). The mixture of water and soda thus formed is dried by means of known methods in order to allow for the use of soda. Soda (NaHCO 3 ) is an important raw material for the glass industry.
The carbon content in the commercial coal is at least around 70%. If this value is taken to be 80%, it means that 1 kg coal contains 0,8 kg carbon. During the combustion, the carbon combines with oxygen to form CO 2 . For 0,8 kg of carbon, 2,93 kg of CO 2 is released. In the factories generating energy from the coal, this value is used as the CO 2 emission factor. CO 2 gas emission per unit electricity generation is 1 ,47 kg/kWh.
Owing to this process step, the CO 2 emission emerging as a result of the combustion is eliminated, and the soda that is generated is provided as an important input for the glass industry. The reaction equation is as follows:
NaOH + CO 2 + H 2 O NaHCO 3 + H 2 O
3. Residual SO 2 Emission: SO 2 that remains after the first step reacts again with the caustic soda (NaOH) and at this stage, the SO 2 emission is completely terminated. The reaction equation is as follows:
NaOH + SO 2 Na 2 SO 4
NaOH + SO 2 NaHSO 4