Campaign time—batch

From diese various estimates, die total batch cycle time t(, is used in batch reactor design to determine die productivity of die reactor. Batch reactors are used in operations dial are small and when multiproducts are required. Pilot plant trials for sales samples in a new market development are carried out in batch reactors. Use of batch reactors can be seen in pharmaceutical, fine chemicals, biochemical, and dye industries. This is because multi-product, changeable demand often requues a single unit to be used in various production campaigns. However, batch reactors are seldom employed on an industrial scale for gas phase reactions. This is due to die limited quantity produced, aldiough batch reactors can be readily employed for kinetic studies of gas phase reactions. Figure 5-4 illustrates die performance equations for batch reactors. 

The total number of batches and the total campaign time for different solvent and feed proportion are presented in Table 10.3. Each case of Table 10.3 corresponds to that of Table 10.2 in terms of solvent and feed proportion. Therefore, for each case the results in Table 10.2 are used to calculate the total number of batches (NB) and the total campaign time (Tcam) using ... 

In the campaign context of a batch plant, it is important to note that throughput and cycle time should include time required for cleaning, transportation and maintenance as these can dramatically affect the overall times and the utilization of any part of a plant. For example, a simple model developed from the AstraZeneca survey calculates the time for a... 

Finally, the process can be broken into several campaigns in which intermediates are manufactured and stored for the next campaign. The final product is manufactured in the last campaign. Essentially all the equipment units of the plants are used in each campaign. This mode of process operation is possible if batch integrity is not essential and/or intermediates are sufficiently stable and can be stored for a certain period of time. 

Intermediate storage de-couples the process into periodically operated subprocesses in the sense that each of the subprocesses can be operated with its own limiting cycle time and batch size. If the storage capacity is sufficiently large to accommodate the intermediate product of an entire production campaign, then the subprocesses can be operated completely independently. Alternatively, the storage capacity can be selected so that it de-couples the... 

An alternative production schedule can be suggested by following a mixed-product campaign, as illustrated in Figure 14.18b. Alternating between batches of Product 1 and Product 2 in Figure 14.14b allows the cycle time to be reduced to 45 h and the makespan to be reduced to 51 h. 

Next to batch production, where exact quantities of a product have to be produced many times over, it is minimum lot sizes that deserve particular consideration. This is usually the case when products are manufactured in large campaigns. Here, products are usually manufactured in a continuous process, with different production processes being combined within the framework of the process chain. When linking the individual production stages to each other it is important to also consider offset times. These can for example include the transportation and analysis time between two production stages. 

Minimal bounds on the production quantity are most often process dependent. Typically, a minimal campaign length is required if for example a critical mass is necessary to initiate a chemical reaction. The same is valid for maximal bounds on the production quantity. The rationale here is that a cleaning operation may be required every time a certain amount has been produced. Finally, batch size restrictions often arise in the chemical industry, if for example the batch size is determined by a reactor load or, as discussed above, the processing time for a certain production step is independent of the amount of material processed. In these scenarios, when working with model formulations using a discrete time scale, it is important that the model formulation takes into account that lot sizes may comprise of production in several adjacent periods. 

Campaign processes have also variable production time. Different to continuous production, campaign production is related to multi-purpose assets, where different processes and products can run on the same production resource and change-over decisions between campaigns need to be taken. Finally, batch processes have a defined lot size, start and end time of production as well as throughput. 

In industrial reactors in most cases enzyme deactivation is important over the relevant time horizon of the reactor operating life, of the campaign, or the catalyst batch. Therefore, many attempts have been made to come to grips with the problem, especially in continuous reactors, or at least to alleviate its effects, by various addition strategies. 

This solvent was used for synthesis during a campaign in a pilot plant It was known to be contaminated with an alkyl bromide. Thus, it was submitted to chemical and thermal analysis, which defined safe conditions for its recovery, that is, a maximum heating medium temperature of 130 °C for batch distillation under vacuum. These conditions were established to ensure the required quality and safe operation. A second campaign, which was initially planned, was delayed and in the mean time the solvent was stored in drums. 

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