Selection process contamination levels

Special safety constraints apply to equipment selection, design, and operation in nuclear reprocessing (269). Equipment should be reHable and capable of remote control and operation for long periods with minimal maintenance. Pulsed columns and remotely operated mixer—settlers are commonly used (270). The control of criticaHty and extensive monitoring of contamination levels must be included in the process design. 

In catalytic processes, such as CO conversion (CO + H20 —> C02 + H2), selective methanisation (CO + 3 H2 —> CH4 + H20) or selective CO oxidation (CO + Vi 02 —> C02), the achievable efficiencies depend on reaction parameters, such as temperature, pressure, volume flow, raw gas concentration and catalyst material. These are capable of achieving contamination levels from 1 % down to a few ppm. The selection of different reaction paths is based on the use of different types of catalyst. 

SELECTION OF SEPARATION PROCESS BY PARTICLE SIZE CONTAMINATION LEVEL... 

Process flow diagrams, stream analyses, contaminant levels, upset conditions, and environmental conditions during shutdowns and start-ups should be evaluated in selecting materials. 

For the process choice, the selection guidelines described above can be helpful, at least in eliminating any inappropriate process. In order to use such guidelines, feed characteristics, contaminant levels, required product purity, allowable impurities, pressure levels and flow rates must be known. These parameters can be used together with experience-based, application-specific guidelines to select the optimum process. 

The strategies for dealing with potential migration of hazardous substances from recycled HDPE are essentially the same as with PET. First, a combination of the selection of starting materials and processing steps can be used to minimize the contamination levels that are present. The first company to obtain a letter of nonobjection from FDA for recycled HDPE in direct food contact was Union Carbide, which later sold the technology to Ecoplast, which also received a letter of nonobjection. ... 

TablelO-1 Typical Contaminant Levels Obtained from Selected Coal Gasification Processes... 

Although there are many biocide alternatives available on the market, for example enzyme technology or bio-dispersants, there appears to be a continued requirement for the use of biocides in order to reduce the levels of microbiological contamination entering the paper making process. The increased awareness of environmental and safety aspects will continue to play an important role on the selection of biocides for paper making processes. The use of legislation to select biocides must be done in parallel with each plants internal risk assessment. No one biocide active will meet all the criteria set out by different European countries and hence the use of these actives must be carefully assessed on a plant by plant basis. 

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