Flue gas conditioning

Physical, thermal, and chemical stability in order to reduce operating costs, solid sorbents must demonstrate stability under flue gas conditions, adsorption operation conditions, and during the multi-cycle adsorption-regeneration process. In particular, stability in the presence of water vapor is essential for the sustainable performance of the solid sorbent. In addition to thermal properties of the solid sorbent, heat capacity and thermal conductivity are also important in heat transfer operations. 

This appears to be the case as is shown in a study of data from two sources. Table VII and VIII describe a 480 Mw and a 575 Mw unit, which were treated subsequently with flue gas conditioning agent. Figure 4 5 are, respectively, the baseline and treated bar graphs of particulate emissions from the unit of Table VII collected by standard Anderson impactors. Similarly, Figure 6 and Figure 7 are the bar graphs (before and after treatment) from the unit of Table VIII. 

Until recently, the potential of chemical flue gas conditioning was not fully appreciated by regulatory agencies. Utilities would try to use chemical conditioning in order to reach compliance levels of emissions. If they failed to do so, they were required to invest in retrofit ESP units or baghouses. During the interim period, most units were allowed to operate under a compliance schedule. This could cover a period of two to three years or until the new equipment was in place and operating. Emissions were, in effect, allowed to continue in an uncontrolled manner. 

The situation is now being reviewed, especially in light of the ready availability and low capital cost of chemical flue gas conditioning. Thus, if chemical conditioning can reduce gross emissions significantly, it may be required as an interim control, even if it does not bring the unit into compliance. 

The activity of the catalysts decreases with time, depending on the flue gas conditions to which they are exposed. The main causes of catalyst deterioration are ... 

Chandan, R. Parker, K.R. Sanyal, A. A review of flue gas conditioning technology in meeting particulate emission standards. Proceedings of the Electric Power 1999 Conference, Baltimore, U.S.A., 1999. 

Thirdly, the evaluation for CO2 capture should be conducted under a simulated or even an actual flue gas condition, rather than the most often used equilibrium CO2 sorption for the current studies. In our opinion, the international facilities in this field should create the benchmarking materials and further the prototypical materials column, which can be used for the evaluation of the CO2 capture performance of newly emerging capture materials on the same standards. Beyond these considerations, the engineering economics of the new materials must be evaluated upon the scale-up of the materials for industrial applications, and economic models must be established to cover lifecycle CO2 separation, capture, and sequestration costs for various technologies. 

To simplify the comparison, only CO2 capture is taken into account without impurities and HjO removal. The assumed flue gas conditions and composition are shown in Table 2.9. The bed dimensions and properties of the base case are detailed in Table 2.10. 

Chemical Stability of Perovskite Membranes Under Flue-Gas Conditions... 

In particular, the project is associated with a 25 tonnes per day COj capture plant, in which the flue gas is at atmospheric pressure and, apart from CO2 (about 11-12%), contains also other gases such as N2, O2, H2O, SO and NOj as well as particulate matter. For post-combustion CO2 capture, the project considers both the existing commercial separation techniques (solvent absorption with amino acid and potassium carbonate solvents) and also novel capture options, such as membrane and adsorption. With respect to the membranes, the programme includes the evaluation of the performance of module configurations under real flue gas conditions, and with respect to the membrane plant, two process options are available ... 

Based on fuel type, flue gas conditions, boiler type, NO removal requirements, new or retroflt application, cost and reliability, the SCR converter in a power plant can be located immediately after the boiler (and the economizer) (high dust arrangement, HD), after the removal of the particulate by the electrostatic precipitator and upstream of the APH Row dust arrangement, LD), and after the particulate collection and/or the removal of sulfur dioxide by a flue gas desulfurization (FGD) system (tail end arrangement, TE) (Figure 3). 

The mercury removal performance of pilot-scale ICDAC and of Norit s FGD carbon were determined in a 0.236 m% (0.25 MWe) pilot plant operated by CONSOL, Inc., Library, PA. The pilot plant can simulate flue gas conditions downstream of the air preheater in a coal fired utility power plant. The flue gas mercury concentration studied (10-15 pg/m ) is typical of utility flue gas concentration. Mercury removals were evaluated in the flue gas duct, which provided a gas residence time of approximately 2 seconds, and in the baghouse, where the solids retention times can be as long as 30 min. Common test conditions were flue gas flow, 0.165 m /s flue gas wet bulb temperature, 50-53°C flue gas composition, 1000 ppmv dry SO2, 10 vol% dry O2, and 10 vol% dry CO2. All tests were conducted with a fly ash obtained from a coal-fired utility boiler firing an eastern bituminous coal. The fly ash feed rate was 4.5 kg/hr (solids loading of 90.6-104.7 gm/dcm ). Mercury removal was determined from the mercury feed rate, the solids (carbon and fly ash) feed rate, and mercury analysis of the feed and recovered solids (by combustion followed by cold vapor atomic absorption spectroscopy). Except where noted, all mercury removal results discussed in this paper include mercury removal by the carbon sorbent and the fly ash. A more detailed description of the pilot test unit is given elsewhere (27]. 

Shanthakumar S, Singh DN, Phadke RC (2008) Flue gas conditioning for reducing suspended particulate matter from thermal power stations. Progress Energy Combust Sci 34 685... 

The flue gas conditions, particularly the flue gas temperature. The conversion to SO3 increases exponentially with the flue gas temperature. 

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