Preparation of high-reactivity absorbent for sulfur dioxide produced in a coal-fired boiler
Date Issued
2004
Date
2004
Author(s)
Wu, Chi-Ying
DOI
zh-TW
Abstract
The number of coal-fired power plants is increasing due to the decreasing reserve of oil. Sulfur dioxide generated by burning coal has resulted in the air pollution and acid rain problems. The reduction of SO2 emission is important to the environmental protection. One way to achieve the goal is by injection of Ca-containing sorbent into the furnace or the duct to react with SO2 to form CaSO4. This technique is simple and easy to use. However, it is challenged by other processes due to its low sorbent utilization. The sorbent reactivity is related to the particle size and the structural properties of the sorbent, as well as the sintering of CaO.
High surface area CaCO3 particles were produced by bubbling CO2 through Ca(OH)2 solution in this study. Effects of several operating variables, including Ca(OH)2 concentration, CO2 flow rate, type and amount of additive, were investigated. The reactivity of CaCO3 toward SO2 was tested in a differential fixed-bed reactor.
The specific surface area of CaCO3 increased with increasing Ca(OH)2 concentration and CO2 flow rate until 2.72wt% Ca(OH)2 and 2.0L/min of CO2,reaching 25.7m2/g. The surface area could be increased to 70~80 m2/g by adding Dispex N40(4.0vol%) and Dispex A40(6.0vol%),but it was slightly reduced by adding FeCl3.
CaCO3 samples prepared with surfactants added were less reactive toward SO2 than those without under the conditions of 60oC and 70%RH due to lower water adsorption capacity; however, they were more reactive at high temperatures( 900 oC) if the calcinations time was minimized to prevent the excessive sintering of CaO.
Subjects
二氧化硫
碳酸鈣
氫氧化鈣
反應動力學
污染防治
reaction kinetics
calcium carbonate
sulfur dioxide
calcium hydroxide
pollution control
SDGs
Type
thesis
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