Mass distribution process streams

If maximum product size is desired, the process stream flow is parallel, with a fresh feed and slurry discharge to product recovery equipment from each crystallizer. Cascaded product flow is avoided because flow through a series of tanks narrows the residence time distribution and the CSD and reduces the mass mean size by reducing the number of larger crystals in the distribution tail. This tail represents the major mass-weighted fraction. Population models have been solved to verify this effect, assuming an equal nucleation rate in each stage (Randolph and Larson 1988). The actual mean in industrial practice is lower because transfer of... 

A mass balance for the plant should be determined to estimate the quantities of each size of stone that will be produced and how each size will pass through the plant. This enables estimates to be made of the quantity and size distribution of each of the process streams and helps to ensure that individual items of plant are correctly specified, particularly in terms of the throughput rate and the input/ output sizes. 

Since higher molecular weight organic compounds were found after the cyclone than further down the process stream the condenser samples and a filter sample from after the cyclone were studied further. Because all the gas chromatograms of condenser samples indicated the presence of components with a wide range of volatility, a portion of the dichloromethane sample collected at 0 C was fractionated by the Sephadex LH-20 column. The mass distribution of this condenser sample and its subfractions are given in Table IV. 

The differences in mass distribution for the Sephadex LH-20 fractions listed in Table IV and Table V are due to different modes of sample collection. The condenser sample contains condensable material that is present in the vapor phase and is not collected by the filter even though the process stream for the filter sample was diluted with nitrogen. 

A vortex tube has certain advantages as a chemical reactor, especially if the reactions are endothermic, the reaction pathways are temperature dependent, and the products are temperature sensitive. With low temperature differences, the vortex reactor can transmit enormous heat fluxes to a process stream containing entrained solids. This reactor is ideally suited for the production of pyrolysis oils from biomass at low pressures and residence times to produce about 10 wt % char, 13% water, 7% gas, and 70% oxygenated primary oil vapors based on mass balances. This product distribution was verified by carbon, hydrogen, and oxygen elemental balances. The oil production appears to form by fragmenting all of the major constituents of the biomass. 

After radon enters the gastrointestinal tract, it is absorbed into the blood stream and then distributes to different organs and tissues (Crawford-Brown 1987). This transfer from the gastrointestinal tract to the blood was dependent upon the emptying patterns of the stomach into the upper intestine, stomach content, fat content of meals, and time of meal in relation to radon ingestion (Hursh et al. 1965 Suomela and Kahlos 1972 Vaternahm 1922 Von Dobein and Lindell 1964). No age-dependent differences in radon distribution from the gastrointestinal tract should be evident due to rapid equilibration in the body (Crawford-Brown 1983). However, changes in the mass of fatty tissue would be expected to affect distribution processes since radon is more soluble in fat than in other tissues (Crawford-Brown 1987). 

This section describes a proposed methodology to evaluate the environmental impact of a chemical industrial process chain in the most accurate way possible. It includes a procedure to compute the LCI based on the concept of eco-vectors [Sonneman et al., 2000], Each process stream (feed, product, intermediate or waste) has an associated eco-vector whose elements are expressed as Environmental Loads (EL, e.g. SO2, NOJ per functional unit (ton of main product). All input eco-vectors, corresponding to material or energy streams, have to be distributed among the output streams of the process (or subsystem). In this sense, a balance of each EL of the eco-vector can be stated similarly to the mass-balance (input = output + generation ). This is the reason why all output streams are labelled as products or emissions. The eco-vector has negative elements for the pollutants contained in streams that are emissions and/or waste. Figure 1 illustrates these ideas for an example of a chain of three processes that produces a unique product. The proposed procedure associates inventory data with specific environmental impacts and helps to understand the effect of those impacts in human health, natural resources and the ecosystem. 

Process parameters of primary importance include roll speed, differential roll speed, roll gap, metal flow rate, metal stream velocity, and melt superheat. The mass median diameter of particles diminishes exponentially as the roll speed increases. It is possible to obtain a smaller mass median diameter when one of the rolls is kept stationary rather than rotating the two rolls at the same speed. Metal flow rate seems to have a negligible effect on the mass median diameter. However, the mass median diameter increases with increasing metal stream velocity, suggesting that the relative velocity of the metal stream to the periphery of the rolls may be a fundamental variable controlling the mass median diameter. The size distribution is approximately constant for the conditions studied. 

Extraction is a process for separating components in solution by their distribution between two immiscible phases. Such a process can also be called liquid extraction or solvent extraction. The former term may be confusing because it also applies to extraction by solid solvents. Since extraction involves the transfer of mass from one phase into a second immiscible phase, the process can be carried out in many ways. The simplest example involves the transfer of one component from a binary mixture into a second immiscible phase — extraction of an impurity from wastewater into an organic phase. In some cases, a chemical reaction can be used to enhance the transfer, e.g., the use of an aqueous caustic solution to remove phenolics from a hydrocarbon stream. 

A theoretical analysis is helpful for understanding the basic characteristics of impinging stream processes and the performances of the related devices. In an impinging stream device, where the residence time distribution of particles is most important is in the impingement zone, because this zone is the major active region for heat and mass transfer between phases in such a device. Unfortunately, it is basically... 

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