Particulate cycle

The main justification for diesel fuel desulfurization is related to particulate emissions which are subject to very strict rules. Part of the sulfur is transformed first into SO3, then into hydrated sulfuric acid on the filter designed to collect the particulates. Figure 5.21 gives an estimate of the variation of the particulate weights as a function of sulfur content of diesel fuel for heavy vehicles. The effect is greater when the test cycle contains more high temperature operating phases which favor the transformation of SO2 to SO3. This is particularly noticeable in the standard cycle used in Europe (ECE R49). 

In a combined power cycle operation, clean (sulfur- and particulate-free) gas is burned with air in the combustor at elevated pressure. The gas is either low or medium heat-value, depending on the method of gasification. 

Removal of Particulate Matter. The amount of particulate entering a cooling system with the makeup water can be reduced by filtration and/or sedimentation processes. Particulate removal can also be accompHshed by filtration of recirculating cooling water. These methods do not remove all of the suspended matter from the cooling water. The level of fouling experienced is influenced by the effectiveness of the particular removal scheme employed, the water velocities in the process equipment, and the cycles of concentration maintained in the cooling tower. 

Uniform depth of loading in dryers and furnaces handling particulate solids is essential to consistent operation, minimum heating cycles, or control of final moisture. After a tray has been loaded, the bed should be leveled to a uniform depth. Special preform devices, noodle extruders, pelletizers, etc., are employed occasionally for preparing pastes and filter cakes so that screen bottom trays can be used and the advantages of through circulation approached. 

The proposed advanced PFBC cycle will permit a turbine inlet gas temperature of over 1535 K (2300°F) by burning a fuel gas produced by pyrolysis of the coal feed. Because the turbine fuel gas must be practicaUy particulate free, it passes through HTHP filters before combustion. The char residue from the pyrolyzer may be burned in a circulating AFBC or PFBC to produce steam for power or heating. The efficiency attainable in an advanced PFBC plant may be as hi as 50 percent (HHV basis). 

Two-stroke cycle Gasoline HC, CO, CO2, NO, particulate Motorcycle, outboard motor... 

Part of the operating cycle of water filters or softeners. It involves the upward flow of water to lift up the media bed to release and wash away dirt and other unwanted particulate matter and to reclassify the media. 

Like sulfur, nitrogen has stable compounds in a wide range of oxidation states and many of them are foimd in the atmosphere. Again, both gaseous and particulate forms exist as do a large number of water-soluble compounds. Table 7-5 lists the gaseous forms. The nitrogen cycle is discussed in Chapter 12. 

Buesseler, K. O. (1998). The decoupling of production and particulate export in the surface ocean. Glob. Biogeochem. Cycles 12,297-310. 

Fig. 14-4 Schematic representation of the transport of P through the terrestrial system. The dominant processes indicated are (1) mechanical and chemical weathering of rocks, (2) incorporation of P into terrestrial biomass and its return to the soil system through decomposition, (3) exchange reactions between soil interstitial waters and soil particles, (4) cycling in freshwater lakes, and (5) transport through the estuaries to the oceans of both particulate and dissolved P.

Films formed with 200 or less cycles generally showed a smooth morphology however, deposits made with 500 or more cycles showed increased amounts of particulates or crystallites. 

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