Ingemar Bjerle

A KINETIC STUDY OF THE DRY SO2-LIMESTONE REACTION AT LOW TEMPERATURE

The dry reaction between SO2 and limestone has been investigated at low temperatures. The study was focused on the wet-dry scrubbing application. Parameters investigated included: temperature: 313–353 K, SO2 concentration: 50–4000 ppm, oxygen concentration: 0–9 percent, carbon dioxide concentration: 0–10 percent, relative humidity 0–92 percent, limestone panicle diameter: 4–100 microns, and limestone conversion: 0–95 percent. The study has revealed that the relative humidity, the particle diameter and the limestone conversion have the most dramatic impacts on the reaction rate. A suggested reaction mechanism is outlined in great detail.

Similarities between lime and limestone in wet—dry scrubbing

Lime is utilized as a sorbent in most commercial wet—dry scrubbing processes for SO2 control, while limestone is not considered to be sufficiently reactive for such a purpose. Faced with the fact that limestone is potentially the least expensive sorbent for SO2 control, a study was conducted to uncover ways to increase the reactivity of this sorbent in order to use it in wet—dry scrubbing applications. The study was focused on a comparison of the reactivity of lime and limestone during the dry reaction period. The conditions which have a major impact on the reactivity include the sorption capacity of water vapour, the BET surface area, the relative humidity and the sorbent utilization. The experiments revealed several similarities between the two sorbents, which led to a number of ways to obtain increased limestone acitivity.

Adsorption of Hydrochloric Lime for Flue Gas Clean Up

The reaction between hydrochloric acid and solid slaked lime was investigated by passing simulated flue gas through a fixed bed reactor. The influence of CO2 and H2O present in the flue gas was studied, as well as the influence of the reaction temperature in the range 423 to 673 K. The reaction was found to be of first order with respect to the two reactants. Expressions to account for the temperature and the CO2 and H2O concentrations were derived from the experimental data.

Activated Wet-Dry Scrubbing of SO2

A new concept for enhancing wet-dry scrubbing of SO2 has been tested on a laboratory and pilot scale. By adding small amounts of promotor, e.g. calcium chloride, to a limestone or lime slurry, a considerable increase in the removal efficiency can be obtained. The experimental findings in a 0.5 MW wet-dry pilot indicate promoted limestone to be a feasible option for SO2 removal when burning low sulfur coals

Modeling of high-temperature desulfurization by Ca-based sorbents

Models for estimating the sulfation of CaO at high temperature are presented. Short-residence-time sulfation is described by a pore size distribution model and long-residence-time sulfation by a particle expansion model. The calculations made agree well with experiments carried out on three different limestones in a TGA, a volumetric reactor and an entrained flow reactor. The pore size distribution model explains the effects of particle size, pore size distribution and partial pressure of SO2, suggesting these three factors to be the most important for CaO conversion. For particles larger than 1-2 mu m, pore diameters of 50-300 Angstrom are desirable. When large particles or long-residence times are used, as in fluidized-bed combustion, the particle expansion model shows the particle size and the sorbent type to be the main factors affecting the reaction

Application of Chemical and Physical Operations in a Circulating Fluidized Bed System

Abstract At the Lund Institute of Technology, a reactor concept has been developed, operating with circulating fluidized beds and segregated gas phases. The reactor has been demonstrated to work in the gasification of black shale, utilizing the char as heat carrier. The reactor principle proposed can also be applied to physical operations such as activated carbon adsorption. In this case, slight constructional modifications are needed. The application of solvent recovery is discussed from a theoretical point of view, utilizing the reactor principle proposed.

A Simple Approximation of the Error Function

Abstract A very simple approximation formula of the error function, with sufficient accuracy for engineering calculations, is proposed in this investigation. The presented form is compared with some of the less sophisticated approximations available in the literature. Aspects such as mnemonic form, computation time, accuracy and ease of inversion are considered.