Multi-stage systems

The multi-stream multi-stage system is a valuable means for obtaining steady-state growth when, in a simple chemostat, the steady-state is unstable eg when the growth-limiting substrate is also a growth inhibitor. This system can also be used to achieve stable conditions with maximum growth rate, an achievement that is impossible in a simple chemostat (substrate-limited continuous culture). 

Despite the advantages of continuous cultures, the technique has found little application in the fermentation industry. A multi-stage system is the most common continuous fermentation and has been used in the fermentation of glutamic add. The start-up of a multi-stage continuous system proceeds as follows. Initially, batch fermentation is commenced in each vessel. Fresh medium is introduced in the first vessel, and the outflow from this proceeds into the next vessel. The overall flow rate is then adjusted so that the substrate is completely consumed in the last vessel, and the intended product accumulated. The concentration of cells, products and substrate will then reach a steady state. The optimum number of vessels and rate of medium input can be calculated from simple batch experiments. 

Multi-stage system for deep desulfurization of fossil fuels [30-33],... 

Assess results Several methods can be applied to minimize the ozone consumption in combined processes of ozonation and biodegradation. For example, the different operational behavior of batch and continuous-flow systems, with the resulting differences in oxidation products, etc. has to be considered, as well as the fact that multi-stage systems for each treatment process may be of advantage over single stage systems. 

Complex K-value and enthalpy models are used only to generate parameters for simple models. These parameters are unique for each stage of a multi-stage system. 

The difficulties associated with highly nonideal multi-stage systems have been overcome by introducing a simple model for the composition dependence of K-values. In keeping with the spirit of the inside-out concept, the parameters of the simple model become outside-loop iteration variables, and are determined by applying the actual models only in the outer loop. Further, they are as independent as possible of the primitive variables. 

Design variations are used to recover paraxylene efficiently from feedstocks (-22% PX) in a multi-stage system, competitive with adsorption-based systems. 

Blood fractionation has been commercially practiced using microfillralion ceramic membranes. A multi-stage system is used where alumina membranes with varying pore... 

Dewatering to depths below those for which gravity lift is adequate can be done with multi-stage systems, as illustrated in Figure 4.4. 

Feed concentration of PX is used efficiently Technology is flexible to process a range of feed concentrations (75 wt%-95 wt% PX) using a single refrigeration system Design variations are used to recover paraxylene efficiently from feedstocks (-22% PX) in a multi-stage system, competitive with adsorption-based systems. 

For a scientific database, permanent control of quality to meet the expectations of users is indispensable. For the GFDB a multi-stage system of quality control was established. 

The efficiency with which the process is carried out in a multi-stage system, compared with a single-stage system operating with and without recycling. 

Ml, M2, Ms are the numbers of moles of isopropyl chloride formed per unit of time in the 1st, 2nd and 3rd reactor, respectively, in g-mole/h M is the total number of moles of isopropyl chloride formed per unit of time in single- or multi-stage systems, in g-mole/h t o is the volumetric feed rate of the propylene, in l./l..h g is the output per unit of reaction volume, in g-moles of isopropyl chloride per litre of catalyst per hour. 

A general equation of this type, obtained for a reactor with a given direction of motion of the flows, can be used to calculate the individual reactions in any multi-stage system with a similar motion of the reagents in the reactor. Here it should be noted that the values of the quantities of the initial and final products for the given reactor should be inserted into the final equation. 

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