Dry absorption of HCl and SO{sub 2} with hydrated lime from humidified flue gas

Journal Article · Fri Oct 01 04:00:00 EDT 1999 · Industrial and Engineering Chemistry Research

DOI:https://doi.org/10.1021/ie9806601· OSTI ID:20001008

Chisholm, P N; Rochelle, G T

The simultaneous absorption of HCl and SO{sub 2} by hydrated lime in a fixed-bed reactor has been studied at conditions simulating humidified flue gas dry scrubbing. At 120 C, an increase in relative humidity from 0% to 19% increased HCl removal and sorbent utilization. At 19% relative humidity (RH), the final loading of hydrated lime was 1.64 mol of HCl/mol of Ca{sup 2+}. From 250 to 1,000 ppm HCl, HCl removal was first order in HCl concentration. When SO{sub 2} was added to the feed gas, the total utilization of the sorbent by HCl and SO{sub 2} was not a function of gas concentration with 250--1,000 ppm HCl and 0--2,000 ppm SO{sub 2}. However, the fraction of the hydrated lime converted by SO{sub 2} was absorbed. Adding 150 ppm NO{sub 2} to the gas stream increased the final SO{sub 2} loading from 0.06 to 0.17 mol of SO{sub 2}/mol of Ca{sup 2+}. As the reactivity of SO{sub 2} and NO{sub 2} increased, the reactivity of HCl decreased slightly as a result of the competition for alkalinity with the other acid gases. The data were modeled using semiempirical flux equations based on a modified shrinking core model. Results from the parameter estimation were used to predict the absorption of HCl and SO{sub 2} on the surface of a bag filter. The predictions indicated that, with a humidified flue gas and 50% sorbent utilization, less than 20% HCl penetration is possible. However, even at the conditions with the greatest SO{sub 2} absorption (250 ppm HCl, 150 ppm NO{sub 2}, and 2.5% O{sub 2}), 90% SO{sub 2} penetration is predicted at 50% sorbent utilization.

• Research Organization: Univ. of Texas, Austin, TX (US)
• OSTI ID: 20001008
• Journal Information: Industrial and Engineering Chemistry Research, Journal Name: Industrial and Engineering Chemistry Research Journal Issue: 10 Vol. 38; ISSN IECRED; ISSN 0888-5885
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
54 ENVIRONMENTAL SCIENCES
ADSORPTION
CALCIUM OXIDES
DECHLORINATION
DESULFURIZATION
FLUE GAS
FOSSIL-FUEL POWER PLANTS
HUMIDITY CONTROL
HYDROCHLORIC ACID
MATHEMATICAL MODELS
NITROGEN DIOXIDE
SULFUR DIOXIDE
WASTE PROCESSING PLANTS