Scale-inhibition Properties Of Polyaspartic Acid

This article summarizes the sources and hazards of sulfur dioxide, and desulfurization technology overview on the research progress. Problems existing in wet flue gas desulfurization (FGD) with lime/limestone technology are analyzed. It is thought to be a feasible solution to scaling and blocking problem to add inhibitors into wet FGD system. Scaling inhibitors in wet FGD system are introduced. We also introduce polyaspartic acid, about its synthesis, properties and applications. In this paper, we studied the scale-inhibiting properties of polyaspartic acid, and we made the comparison of those of polyacrylic acid (PAA) and 2-phosphonobutane-1,2, 4-tricarboxylic acid (PBTCA). In slurry of wet FGD system, the scaling laws under these inhibitors and the scale inhibiting process of PASP were analyzed.By means of Static Scale-inhibiting method, the scale-inhibiting properties of PASP, PAA and PBTCA were detected. Simultaneously, scaling laws under these inhibitors were analyzed by means of rotation specimen method. Results showed that these inhibitors had threshold effect as the dosage of inhibitors increasing. The order of scale inhibition effects against CaCO3 of three inhibitors was as follows: PBTCA>PAA>PASP. As water-bath temperature increased and reaction time extended, scale inhibition effects against CaSO4 of these inhibitors increased at first, and then decreased. pH had little impact on scale inhibition effects against CaSO4 of PAA and PBTCA. When pH>7.0, the influence of pH on scale inhibition effects against CaSO4 of PBTCA can be negligible. When pH6.0 and 5.0, that can be visible.The effect of several factors on scale inhibition effect of polyaspartic acid in wet flue gas desulphurization system with lime is discussed in this paper. Experimental data demonstrated that when water-bath temperature, reaction time and stirring speed increased, the mass of hanging on-chip scaling increased at the began, and then decreased as the dosage of inhibitors increasing. Water-bath temperature, reaction time and rotating speed played an important role on scaling; scale inhibition effect of polyaspartic acid in wet flue gas desulphurization system with lime was the combined action of water-bath temperature, reaction time, rotating speed and scale inhibitor. Under the same experimental conditions (60℃,5h,100 r/min), PASP, PAA and PBTCA showed the similar variation of inhibition effect. Under the same conditions (60℃,5h,100 r/min), the mass of stainless hanging on-chip scaling was bigger than that of granite hanging on-chip. The structures and properties of scale samples crystals were investigated by SEM (scanning electron microscopy) and xrd (X-ray diffraction), the analyses showed that the structure of scale samples crystals may vary with or without PASP. With PASP, it was easy to form granular crystals and agglomerate together, not easy to adhere to slide surface. So it came to scale inhibition. The scale inhibiting process of PASP was analyzed.