Solvent based slurry

An interesting extension of the range of vacuum filters is the capillary disc filter (Figure 4.26). This is a continuously operating, capillary action, ceramic dewatering filter, which eliminates the need for separate filter cloths. The filter medium is a disc, formed from two circles of sintered alumina, joined at their circumferences. The filter has several such discs mounted on a central horizontal shaft. The medium is practically inert in most solutions, and may be used in a broad range of water-based and solvent-based slurries. In operation, as the microporous ceramic discs rotate through... 

The absorption technique using hot potassium carbonate has also been developed to capture C02 (Probstein and Hicks, 1990). The chilled ammonia process is another solvent-based C02 capture technology where ammonia carbonate slurries are used to capture 90% of the C02 in the gas stream mixture gas forming ammonia bicarbonate in the process. A pilot-scale chilled ammonia unit for 5 MW equivalent flue gas capture is under construction by ALSTOM and EPRI. Although this process is developed for a combustion system, the results will provide valuable information for the future development of such a process for hydrogen production. According to ALSTOM, commercial products on chilled ammonia process will be available by 2010 (Alstom, 2007). 

Commercial oxide slurries are available with different chemistries. The most common ones are the NaOH-based, the KOH-based, and the NH40H-based slurries. The NaOH-based slurry is the best medium for OH groups because the NaOH solvent is cheap and stable. However,... 

As can be seen in the NEDOL process in Figure 12.4, pulverized coal and 2% 4% by weight iron-based catalysts are first slurried together with recycled solvents. The slurry is mixed with H2 and preheated before it is delivered to the liquefaction reactor. The tubular up-flow reactor typically operates at temperatures of... 

Polyphase FP44 preservative, slurries Dowlcll QK-20 Nuosept 495 Nuosept S Taurlne-KWT Taurlne-MBT preservative, solvent-based coatings Fungltrol 334 Fungltrol Tlnox preservative, stains Troysan 186-11 Troysan 192-11 preservative, starch-based systems Nuosept S preservative, stock Busan 1210... 

All of these UV-curable systems have very different chemistries than those used in solvent-based systems. Most contain a dispersant, a plasticizer (not necessary in all cases), a photopolymerizable binder, and an initiator to activate the UV curing. A typical binder/initiator system found in the literature is a polyester acrylate binder and an initiator such as 2-hydroxy-2methyl-l-phenyl-propan-l-one. The binder is a liquid low-viscosity monomer diluted into hydroxy-ethyl methacrylate. Most of the UV-curable systems contain an acrylate monomer of some sort, since they have relatively low viscosities (100 mPa s or cP) and excellent reactivity with the UV radiation. The low viscosity allows the preparation of ceramic slurries with a relatively high solids loading, and the resulting high-density green sheets have excellent mechanical properties. 

Direct-Liquefaction Kinetics All direct-liquefac tion processes consist of three basic steps (1) coal slurrying in a vehicle solvent, (2) coal dissolution under high pressure and temperature, and (3) transfer of hydrogen to the dissolved coal. However, the specific reac tion pathways and associated kinetics are not known in detail. Overall reaction schemes and semiempirical relationships have been generated by the individual process developers, but apphcations are process specific and limited to the range of the specific data bases. More extensive research into liquefaction kinetics has been conducted on the laboratory scale, and these results are discussed below. 

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