Long-term operation

The filter media must be a source of inorganic nutrients for the microbes. In cases of long-term operation, inorganic nutrients can be periodically added to the bed. 

When a test run is performed using the actual materials for the toll, it is a prime opportunity for the toller and the client to document the capability of the equipment, instrumentation, and process steps. During such a test, frequency of sampling may be increased, additional analyses performed and yield capabilities checked to find the optimum setpoints and timing for the toll process. Health, safety and environmental staff may choose to provide close coverage of the test run to evaluate areas for improvement during the actual startup and long term operation. 

Graphitic anodes which have been "prefilmed" in an electrolyte "A" containing effective film-forming components before they are used in a different electrolyte "B" with less effective film-forming properties show lower irreversible charge losses and/or a decreased tendency to solvent co-intercalation [155, 201, 202], However, sufficient insolubility of the pre-formed films in the electrolyte "B" is required to ascertain long-term operation of the anode. 

Notwithstanding the seriousness of these pre-boiler problems, however, it is material (especially iron oxide corrosion debris) originating in the condensate system, then transported back to the boiler itself, which carries the greatest risks of long-term operational problems. 

Sol-gel technique has also been applied to modify the anode/electrolyte interface for SOFC running on hydrocarbon fuel [16]. ANiA SZ cermet anode was modified by coating with SDC sol within the pores of the anode. The surface modification of Ni/YSZ anode resulted in an increase of structural stability and enlargement of the TPB area, which can serve as a catalytic reaction site for oxidation of carbon or carbon monoxide. Consequently, the SDC coating on the pores of anode leads to higher stability of the cell in long-term operation due to the reduction of carbon deposition and nickel sintering. 

Electrolyte loss occurring in long-term operation of MCFC is another problem to be solved for practical application of MCFC. For commercialization, the MCFC should show stable performance over 40,000 hours. Electrolyte loss in MCFC is caused by various factors, e.g., corrosion of components, creepage, reaction with cell components and direct evaporation. These... 

Long-term operation may be required to achieve remediation goals for large plumes, complex hydrogeologies, or if an active source remains in place. 

These factors may influence the specific aboveground treatment technology that is selected, the possible need for multiple aboveground treatment processes (treatment trains), and the need for pretreatment of groundwater or posttreatment of off-gas. Also, as with the extraction component, the presence of an active source area may result in the need for long-term operation of aboveground treatment systems. 

The activity of air electrodes with pyrolyzed CoTMPP catalysts is investigated as a function of the heat treatment temperature. In Figure 13 we have presented the initial curve, and the curves obtained after long-term operation of the electrode at c. d. 100 mA/cm2. It is seen that a maximum in the activity is obtained at pyrolysis temperature ca. 800°C, the activity being practically preserved with the time of operation of the air electrode. 

Gamburzev S., Iliev I., Kaisheva A., Steinberg G., Mokrousov L., Behaviour of carbon wetproofed electrodes during long-term operation in alkaline electrolyte, Elektrokhilija, 1980 16 1069-72. 

Overall, the newly developed alloys, such as Crofer 22 APU and ZMG 232 (developed by Hitachi Metal, Ltd.) [142, 143], are promising candidate alloys for SOFC interconnect applications, but their stability during long-term operation at 650 to 800°C remains questionable. 

Long-term operation monitoring may be performed to evaluate the potential for injection well fouhng, pH changes, and temperature variations and to identify unexpected variables. 

Engineering tests. These tests demonstrated the operation of modifications to the existing energetics feed system and SILVER II plant to eliminate the operational problems discussed in AEA s final report for Demo II (AEA, 2000). They also demonstrated the long-term operation of a 12-kW SILVER II system on feeds of agent simulant and energetics. 

Finding (Blue Grass) AEA-3. Long-term operation of the SILVER II cell membrane on all the required feed streams has not been demonstrated. Because the SILVER II process is the primary treatment process for agent and energetics, the committee is particularly concerned that the life of the cell membranes, on which the efficacy of the SILVER II process depends, has not been demonstrated. 

Long-term operation on H and GB feeds containing chlorine and fluorine has not been demonstrated. The agent simulant, DMMP, does not contain these elements. 

Surface-modified silica gels are used for a variety of separations, but organic polymer-based stationary phase materials are more useful for long-term operations, such as for an amino acid analyser and size-exclusion liquid chromatography. 

Based on the present understanding of the effect of sulfur on MCFCs, and with the available cell components, it is projected that long-term operation (40,000 hr) of MCFCs may require fuel gases with sulfur " levels of the order 0.01 ppm or less, unless the system is purged of sulfur at periodic intervals or sulfur is scrubbed from the cell burner loop (76). Sulfur tolerance would be approximately 0.5 ppm (see Table 6-3) in the latter case. Considerable effort has been devoted to develop low-cost techniques for sulfur removal, and research and development are continuing (80,81). The effects of H2S on cell voltage are reversible if H2S concentrations are present at levels below which nickel sulfide forms. 

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