A new semi-dry desulfurization process using a powder-particle spouted bed

Kinetics of flue gas desulphurization at low temperatures: fly ash/calcium (31) sorbent behaviour

Modeling and experimental studies of SO2 absorption in coaxial cylinders with impinging streams: Part I

Desulfurization in the gas-continuous impinging stream gas–liquid reactor

Kinetics of flue gas desulfurization at low temperatures: nonideal surface adsorption model

The Coolside desulfurization process is a dry sorbent injection technology developed for retrofit SO/sub 2/ control in coal-fired utility power stations. The process is low in capital and space requirements since, in its ideal configuration, the existing ductwork and particulate collector are used as the SO/sub 2/-sorbent reaction spaces. It has been developed through laboratory and 1 MW-scale field tests using hydrated lime as the primary process sorbent by Conoco Coal Research Division, the research branch of Consolidation Coal Company. The field work showed promising results with observed SO/sub 2/ removal ranging up to 80%. In order to optimize the process performance through improved understanding of the process fundamentals, Conoco constructed and is operating a 0.15 MW pilot test unit. This paper describes the results of a process variable test program, a first series of tests made in the pilot unit, and the unit operability observed during the test work.

Pilot process variable study of coolside desulfurization

This paper describes a dry sorbent injection SO2 abatement process with the potential to significantly enhance desulfurization performance over that of existing in-duct injection technology such as the Coolside process. The Advanced Coolside process was developed by CONSOL Inc. and is being tested in a pilotscale project, partially funded by the U.S. Department of Energy (DOE). The goals of this process development effort are to increase the applicability of sorbent injection technology as a compliance option for coal-fired boilers for the 1990 Clean Air Act Amendments and to reduce total process SO2 control costs. Specific performance objectives are to achieve 90% SO2 removal and 60% sorbent utilization efficiency, while retaining the low-capital cost and retrofit advantages inherent to in-duct sorbent injection technology. The Advanced Coolside process concept involves flue gas humidification to near the adiabatic saturation point combined with fly ash removal using a gas/liquid contacting device, followed by injection of a sorbent (e.g., Ca(OH)2) into the highly humid flue gas with collection by the existing particulate collector. High SO2 removal and sorbent utilization efficiency are possible with hydrated lime when the flue gas is nearly saturated with moisture. Sorbent utilization is further improved by recycle, and the potential for improvement by the use of recycle is increased with removal of the fly ash before sorbent injection. Further, testing indicates that pre-treatment of the recycle sorbent before reinjection can improve process performance. Because flue gas is humidified completely before sorbent injection, the existing duct configuration may not limit process retrofit potential. The heat of reaction between SO2 and Ca(OH)2 heats the flue gas before the existing particulate collector. Current pilot test data indicate that the Advanced Coolside process performance objectives are achievable. On-going process development work includes design optimization for the contacting device, improving efficiency of sorbent recycle, and optimization of sorbent performance.

Advanced coolside desulfurization process

Mercury control technology options for coal-fired boilers are ill-defined. Commercial development of mercury emissions control technologies has centered on high concentrations of mercury compared to the levels present in the flue gas from coal combustion, typically 5 to 10 {mu}g/m{sup 3}. In addition, most mercury in these commercial applications (medical waste and municipal solid waste incinerators) is in the form of HgCl{sub 2}; flue gas from coal-fired units contains both ionic and elemental mercury. Reaction mechanisms may be different for these two species. Development work at the lower concentrations has centered on small scale, fixed-bed, laboratory studies. Recent tests at coal combustion sources with sorbents such as lime and activated carbon have shown some mercury removal. However, neither the laboratory nor combustion tests completely address process design issues. In the laboratory studies, the actual process conditions are very different from those with coal; while in the combustion tests, it is difficult to vary the conditions. In addition, data reliability is poor because of the difficulty of mercury sampling and analysis.

W.A. Rosenhoover

Papers

Pilot process variable study of coolside desulfurization

Advanced coolside desulfurization process

Pilot plant study of mercury control in flue gas from coal-fired boilers