Batch process profile

Figure 8 Automated high-throughput RNA analysis by capillary electrophoresis. Typical batch processing profiles of a 96-well sample plate. Total RNA sample preparations from rice (traces 1-76 from top), arabidopsis (traces 77-95), and yeast (trace 96) 6 pL each in 96-well plate. Conditions 50-pm-i.d. capillary, =10 cm (L = 30 cm) sieving medium, 1% PVP (polyvinylpirrolidone, MW= 1.3 MDa), 4 M urea, 1 xTBE, 0.5 pM ethidium bromide =500 V/cm 25°C. RNA samples were diluted in deionized water and denatured at 65°C for 5 min prior to analysis. Sample tray was stored at 4°C in the CE instrument during processing. Injection vacuum (5 s at 3.44 kPa). Separation matrix was replaced after each run, 2 min at 551 kPa. (Reproduced with permission from Ref. 102.)...

Like enzymes, whole cells are sometime immobilized by attachment to a surface or by entrapment within a carrier material. One motivation for this is similar to the motivation for using biomass recycle in a continuous process. The cells are grown under optimal conditions for cell growth but are used at conditions optimized for transformation of substrate. A great variety of reactor types have been proposed including packed beds, fluidized and spouted beds, and air-lift reactors. A semicommercial process for beer used an air-lift reactor to achieve reaction times of 1 day compared with 5-7 days for the normal batch process. Unfortunately, the beer suffered from a mismatched flavour profile that was attributed to mass transfer limitations. 

The PBL reactor considered in the present study is a typical batch process and the open-loop test is inadequate to identify the process. We employed a closed-loop subspace identification method. This method identifies the linear state-space model using high order ARX model. To apply the linear system identification method to the PBL reactor, we first divide a single batch into several sections according to the injection time of initiators, changes of the reactant temperature and changes of the setpoint profile, etc. Each section is assumed to be linear. The initial state values for each section should be computed in advance. The linear state models obtained for each section were evaluated through numerical simulations. 

The exact nature of each of these additives appears to be trade secret information since none of the Material Safety Data Sheets describing the hydraulic fluids presented in this profile identify these materials. In addition, no information concerning the exact production methods used in manufacturing these hydraulic fluids was located in the available literature. Nonetheless, they are probably manufactured in batch processes and then tested to insure that they conform to the specifications for which they are sold. The number, nature, and amount of each additive used in a batch may depend on availability, cost, or performance. 

In continuous processes, parameter profiles might be required to be optimized through space. In batch processes, parameter profiles might need to be optimized through time. How can this be achieved ... 

The control variables can be constrained to fixed values (e.g. fixed initial temperature in a temperature profile) or constrained to be between certain limits. In addition to the six variables dictating the shape of the profile, ttotai can also be optimized if required. For example, this can be important in batch processes to optimize the batch cycle time in a batch process, in addition to the other variables. 

A second system, the removal of volatiles by vacuum, can be set up in two ways either as a flow-through or as a batch process. As a flow-through process, the sample is drawn continuously through the system, and the gases taken off by the vacuum pass through a sampling loop. Periodically, the material in the loop is injected into the gas chromatograph. In this manner it is possible to derive almost continuous profiles of volatile hydrocarbon concentrations [19]. 

RASHED, M.S., BUCKNALL, M.P., LITTLE, D., AWAD, A., JACOB, M., ALAMOUDI, M., ALWATTAR, M., OZAND, P.T., Screening blood spots for inborn errors of metabolism by electrospray tandem mass spectrometry with a microplate batch process and a computer algorithm for automated flagging of abnormal profiles, Clin. Chem., 1997,43,1129-1141. 

A simple model of the batch process was compiled using a commercial spreadsheet program, using finite time elements. A macro was written to obtain convergence of start and end of batch conditions. This model was simple to construct and proved satisfactory in calculating the batch profiles for operation without, and subsequently with, the catalytic reactor on-line. The values obtained for operation without the inloop catalyst compared well with plant values. 

The condition for the practical implementation of such a feed control is the availability of a computer controlled feed system and of an on-line measurement of the accumulation. The later condition can be achieved either by an on-line measurement of the reactant concentration, using analytical methods or indirectly, by using a heat balance of the reactor. The amount of reactant fed to the reactor corresponds to a certain energy of reaction and can be compared to the heat removed from the reaction mass by the heat exchange system. For such a measurement, the required data are the mass flow rate of the cooling medium, its inlet temperature, and its outlet temperature. The feed profile can also be simplified into three constant feed rates, which approximate the ideal profile. This kind of semi-batch process shortens the time-cycle of the process and maintains safe conditions during the whole process time. This procedure was shown to work with different reaction schemes [16, 19, 20], as long as the fed compound B does not enter parallel reactions. 

Overalkylation can lead to tertiary alcohol formation by consecutive reaction [29]. Product quality demands to keep this impurity level <0.2%. Microreactor operation yielded the overalkylated alcohol follow-up product at 0.18%, whereas level of impurity for the batch process was 1.56% [29]. The reason is probably the lower back-mixing in the microflow system, with concentration profiles being less deteriorated from ideal that is, no excess of alkylating agent is generated locally to promote the follow-up reaction. 

Similar to batch processes, the transfer of number of stages is not always as perfect, as in the case of enantiomeric separation of EMD53986. If significant deviations between the concentration profiles are observed, another component has to be taken as reference component so that the total number of stages of every component in the new plant is greater or equal to the number of stages in the old plant (Eq. 7.36). 

Fig. 3.25 Galactosylation profile of three different monoclonal antibodies produced in batch and fed-batch processes. The profiles were made by MALDI-TOF analyses.

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