Reactivity of the solid sodium carbonate towards the gaseous hydrogen chloride and the sulphur dioxide

Abstract

The rate of reaction of the anhydrous sodium carbonate with the hydrogen chloride and its mixture with sulphur dioxide was measured in an integral fixed-bed reactor. Reactivity of the active sodium carbonate towards the hydrogen chloride is lower as compared with its reactivity towards the sulphur dioxide. A relationship was found between the reactivity of the solid and the way of its preparation. The inactive form of the sodium carbonate is inactive towards both the sulphur dioxide and the hydrogen chloride. The active form of the sodium carbonate exhibits towards the hydrogen chloride a reactivity which is by orders of magnitude higher than that of the inactive form. The variation of the ratio of partial pressures of the hydrogen chloride and the sulphur dioxide in the reaction with the sodium carbonate does not affect significantly the total degree of the solid conversion, which attained a value of 65% in laboratory experiments. The degree of gas purification from the acid components did not fall under a value of 99% up to a solid conversion of about 50% at a mean gas contact time of about 10-2 s.

HCI Sorption by Dry NaHCO3 for Incinerator Emissions Control

“…The unusual collection efficiency behavior shown by the 10 micron particles at 275° F is also present at 375° F. Mocek et al (1983) found a similar increase in HCI collection efficiency with time when testing predecomposed NaHCC>3. This effect may occur for all particle diameters, but the longer time intervals for which the impingers are operated during the 30 minute tests averages the instantaneous collection efficiency too much to detect it.…”

“…6 The HC1 concentration in the reactor outlet gas was monitored during the 10-20 hour runs to determine the sorbent conversion at 1 percent breakthrough. Karlsson et al reported that the conversion of Ca(0H)2 to CaCl2 at 1 percent breakthrough increased from 14 to 28 percent as the temperature was increased from 300°F to 480° F, and increased to 47 percent by raising the temperature to 750° F. Mocek et al (1983) tested HC1 sorption by predecomposed NaHCC>3 particles (250-350 microns) in an integral fixed-bed reactor at 300° F. 7 The absolute HC1 gas concentration and total gas flow rate were not specified; the values were presented using dimensionless variables. Nitrogen was used as the carrier gas.…”

Experimental Investigation of the Reactivity of Sodium Bicarbonate toward Hydrogen Chloride and Sulfur Dioxide at Low Temperatures

“…With respect to reactivity with HCl, a pioneering study by Mocek et al 15 documented that Na 2 CO 3 from reaction R1 has a reactivity toward HCl (1000 ppm) at 150°C that is orders of magnitude higher than that of nonthermally activated Na 2 CO 3 . Fellows and Pilat 16 investigated the sorption of HCl (415 or 760 ppm) in a broad temperature range (100−280°C).…”

Reaction kinetics of hydrogen chloride with sodium carbonate

“…It is also known from thermodynamic Table 2 Solid conversions in the multilayer fixed bed vs. particle diameter (d p ) and acid gas concentration calculations (Verdone and De Filippis, 2004;Mura and Lallai, 1995) that the presence of water vapour in the gas influences at a certain extent the equilibrium concentration of the gaseous HCl over an NaCl/Na 2 CO 3 solid system. However, the HCl equilibrium concentration in the range of interest (200-600 • C) is extremely low and the effect of the presence of water or change in its concentration in the gas phase can be neglected (Mocek et al, 1983;Duo et al, 1996). In order to investigate how the sodium carbonate particle size affects the HCl removal, some runs were carried out using sodium carbonate with a particle diameter of 120 m. The runs were conducted at temperatures of 300, 400 and 500 • C with a HCl concentration in the feed equal to 6000 ppm.…”

“…Reactivity of solid sodium carbonate towards the gaseous hydrogen chloride was studied experimentally by Mocek et al (1983) in an integral fixed-bed reactor at 150 • C. These authors found an average grade of solid conversion in experiments with dry and humid hydrogen chloride (1000 ppm) in the range from 44% to 49%. Dvirka et al (1988) from theoretical calculations predicted that the reduction of hydrogen chloride concentrations from 208 to 5 ppm at 315 • C by contact with sodium carbonate requires less than 0.001 s. Laboratory measurements of HCl collection efficiency conducted by Fellows and Pilat (1990) in a fixed bed of NaHCO 3 showed that HCl sorption increased strongly increasing temperature from 107 to 288 • C, but was only weakly dependent on particle diameter.…”