Combined Feed Ratio

3 Combined Feed Ratio The recycle ratio is defined as follows  

Modem coking units operate at 10% or less combined feed ratio (CFR) (as low as 3%) to increase unit throughput. Recycle ratio is used to control the endpoint of the coker gas oil. An increase in the recycle ratio causes 

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In order to process SRC in the pilot plant equipment without using an extraneous solvent, a portion of the hydrotreated product was recycled to the feed reservoir as diluent. Recycle was essentially internal, and SRC and hydrogen were the only net feeds to the system. Pulverized SRC was added to the hot reservoir at a ratio of two parts SRC to three parts recycled product (combined feed ratio = 2.5). Vigorous stirring ensured that no undissolved solids were taken into the feed pump system. 

From another standpoint, if the rigorous flash-type calculation, say, is to be used at each stage for a fixed vapor to combined feed ratio, then V" has to vary as the composition of the combined feed input to the cell varies. In turn, the K-values would vary. 

The liquid recycle rate is normally adjusted as a ratio with fresh feed. This variable is called combined feed ratio (CFR), and is defined as follows ... 

FC and TC = flow and temperature controllers, respectively SP = setpoint S/F = steam/feed ratio x = multiplication of signals and + = sum of signals, (a) Additive (b) multiphcative and (c) combined additive and multiphcative. 

The next products developed were the thermoplastics made by vinyl polymerization. Vinyl chloride, and vinyl acetate copolymers known as Vinylite, was one of the first produced by Carbide and Carbon. It had been worked on in Europe and had also been worked on by Ostromysslenski, a chemist with the U. S. Rubber Company. The Carbide chemists realized at an early date that to get a uniform composition it was necessary to adjust the feed ratios of the two monomers to get a proper combination in the reactor to give a constant composition to the product. The next major development of a vinyl product was in the development of Lucite or Plexiglas polymers, which are clear, strong plastics. 

It is a combination of exothermic steam reforming and endothermic partial oxidation applying a stoichiometric feed ratio which allows for an overall zero energy balance. As the exothermic reaction is faster, a hot-spot is very common in... 

Bot ial for Cost Reduction, The process and plant design discussed here has not yet been optimized for cost efficiency. Selection of process pres ire, solvei /feed ratio, extractor configuration and cycle, removal of extracted components from solvent, and many other factors should be done using a combination of technical and economic inpact. 

As the heptane rate is increased, the separation is improved, as indicated by the rising ratio of ethane to propane in the vapor product. At the same time, however, the ethane recovery, expressed as the ethane flow rate in the vapor, goes down as the heptane rate is increased. This is a limitation of the single-stage separation process. At a certain heptane rate the entire combined feed is condensed, leaving a single product—a liquid at its bubble point. 

The entrainer-to-feed ratio is calculated by combining the last two equations ... 

To begin the calculations the column variables must be first initialized to some estimated values. Simple methods can be used for this purpose, based on the column specifications and possibly supplemented by shortcut methods. The column temperature profile may be assumed linear, interpolated between estimated condenser and reboiler temperatures. The values for Lj and Vj may be based on estimated reflux ratio and product rates, assisted by the assumption of constant internal flows within each column section. The compositions Xj- and T, may be assumed uniform throughout the column, set equal to the compositions of the liquid and vapor obtained by flashing the combined feeds at average column temperature and pressure. The other variables to be initialized are Rf,Rj, and Sj, which are calculated from their defining equations. The values for Qj may either be fixed at given values (zero on most stages) or estimated. 

Fortunately the combination of above variables required to produce 900-f Btu gas is easy to achieve in practical reactor systems. For example, the reactor can operate at gas transmission-line pressures, both the gas coal feed ratio and the methane concentration in the feed gas allow operation at carbon conversion levels resulting in balanced plant opera-... 

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