Enhanced Wet Flue Gas Desulfurization Properties by Additives of Organic Acids, Organic Salts, Inorganic Salts, and Organic Amines

Abstract

In order to enhance wet flue gas desulfurization efficiency and reduce cost, the effects of different series of additives (typical organic acids, organic salts, inorganic salts, organic amines, and their mixture) on the desulfurization properties, including pH buffering characteristics of slurry, dissolution characteristics of CaCO 3 , oxidation characteristics of CaSO 3 , desulfurization efficiency, and economic cost were investigated in this work. The results show that the pH buffering capacity is sodium benzoate ≈ Na 2 SO 4 > adipic acid > double oxazine. The dissolution promoting effect of CaCO 3 is acetic acid > double oxazine ≈ sodium acetate > MgSO 4 . The additives that can significantly promote the oxidation of CaSO 3 are adipic acid, citric acid, acetic acid, MgSO 4 , and Na 2 SO 4 . Without an additive, the desulfurization efficiency of CaCO 3 slurry decreased to 85.87% after 4 h. After the addition of the composite additive (CA-3), the desulfurization efficiency of CaCO 3 slurry remained 96.53% for 4 h, increasing by 10.66%. The main reasons for the enhancement in the desulfurization process may be a collection of three factors: the reversible hydrolysis reactions of acetic acid and sodium acetate, the formation of an acid−base conjugate system by sodium benzoate, and the formation of a neutral ion pair MgSO 3 by MgSO 4 in the slurry. In addition, the composite additive has been used in the Dabie mountain power plant of China. The economic benefit analysis shows that the desulfurization unit of 4 × 640 MW coal-fired power plant can save 1.26 million dollars per year by composite additive.

Effect of organic additives on NO₂ removal in the simultaneous absorption of SO₂ and NO₂ into limestone slurry

“…Removal rate (%) =         × 100 (1) where C in refers to the gas concentration injected into the reactor, and C out refers to the gas concentration discharged from the reactor. During the reaction process, a predetermined amount of slurry was collected and vacuum-filtered to analyze four types of anions in the limestone slurry, SO .…”

“…1. Introduction SO 2 and NO X emitted during the combustion of fossil fuels used in power plants are considered important substances in air pollution control, as they react with water vapor to form acid rain or generate particulate matter through photochemical reactions [1]. Processes such as wet flue gas desulfurization (WFGD), nonthermal plasma, membrane separation processes, and catalytic absorption have been proposed to simultaneous absorb SO 2 and NO X [2][3].…”

SO2 Adsorption and Kinetics Analysis during Supported Triethanolamine Acetate Ionic Liquid Desulfurization

“…The commonly used circulation desulfurization technologies include activated carbon desulfurization, organic amine flue gas desulfurization, , and ionic liquid desulfurization. , Ionic liquids (ILs) are salts comprising ions with a low melting point and are in a molten state at room temperature (21–25 °C). They are characterized by low vapor pressure, good solubility, and strong thermal stability.…”