Abstract
The cement industries alone emit 5% of the world’s total green house gases. In Ethiopia, the current CO2 emission from this sector is about five fold of the countries overall CO2 emission in 2002. Mugher cement factory (MCF), a case study plant in this paper, alone emits 463,844 tons of CO2/year on average based on emission test and mass balance performed. Yet it accounts for less than 3% of the current CO2 emission from this particular industry in the country. Of those technical approaches, separation of CO2 before it joins the immediate atmosphere is getting wide spread interest. In relation to this, experiment on absorption of CO2 is conducted to determine the effect of flow rate of the gas sample, concentration of the sodium hydroxide, flow rate of solvent and temperature of absorbent on absorption of CO2 using the “Armfield” gas absorption column followed by the titrimetric analysis. Except temperature of solvent, all study variables showed strong relation with the amount of carbon dioxide absorbed (with a P-value < 0.05). Uniquely, this study has evaluated the potential for sodium bicarbonate production from the CO2 absorbed using gravimetric analysis. It is also possible to recover over 28% crystal sodium bicarbonate. Key words: Green house gas, CO2, absorption, caustic soda, sodium bicarbonate.
Highlights
It is estimated that the global average temperature will rise between 1.4-5.8°C by the year 2100
The composition expressed in percentage by volume of those gases tested many times showed close results and the CO2 is found to be 20% on average (Table 1)
This study has showed rate of absorption to be indirectly related to solvent temperature but it was not statistically significant
Summary
It is estimated that the global average temperature will rise between 1.4-5.8°C by the year 2100. The contributors to greenhouse effects are carbon dioxide (CO2), chlorofluorocarbons (CFCs), methane (CH4) and nitrous oxide (N2O). The contribution of each gas to the greenhouse effects is CO2- 55%, CFCs- 24%, CH4- 15% and N2O- 6% (Moazzem et al, 2012). Hydraulic ( portland) cement, the binding agent in concrete and most mortars, is an important construction material. Portland cement is made primarily from finely ground clinker, a manufactured intermediate product that is composed predominantly of hydraulically active calcium silicate minerals formed through hightemperature burning of limestone and other materials in a Abbreviations: CN_aver, Average sodium carbonates concentration (g-mole/litters); CO2_Xaver, average carbon dioxide absorption rate by the liquid (g-mole/second); Qg, gas flow rate (litter/minute); Ql, liquid flow rate (litter/minute); Rab, rate of absorption (mole/second); GJ, Giga-Joule; Gt/y, Giga-ton /year; MCF, Mugher Cement Factory; Conc, concentration (mole)
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