Batch structure

Batch stirred tank H SCL/oleum aromatic sulfonation processes, 23 541 Batch stirred tank SO3 sulfonation processes, 23 543 Batch structural models, 20 705 Batch sulfonation, 74 387 Batch suspension cell culture systems, 5 349-352... 

Figure 7.34 Comparison between continuous and batch reactive equipment. All three continuous reactors required to form the AR share equivalent batch structure. Adapted from Ming et al. (2013).

Optimal Continuous Structure In Section 7.2.1, we examined the nature of the optimal continuous reactor structure for the three-dimensional Van de Vusse reaction scheme. Let us now investigate the associated optimal batch structure for the same problem. This exercise will demonstrate the role that DSRs, and by extension fed-batch reactors with varying a policies, play in the formation the AR boundary. 

The system under investigation is identical to the system established in S ection 7.2.1. As a result, the AR for the batch system will be constructed in the same space and feed point (Cf = [CAf, CBf, Cof] = [1,0, 0] mol/L). We are also able to utilize the optimal reactor structures, developed in Section 7.2.1, and convert them to batch structures without the need to perform additional analysis. The critical a policy for the DSR, given in Section 7.2.1.5, will be used for the F/V policies in the batch system. 

S.2 Conversion to Batch Since the AR is defined by two parallel continuous structures, it follows that, at most, two batch structures are required to achieve all points on the AR boundary as well. Figure 7.37 provides the necessary conversion from continuous to batch for the Van de Vusse system. A one-to-one correspondence between batch and continuous equipment is observed. For both optimal batch structures, a fed-batch reactor with a varying a pohcy is seen to contribute to the overall set of achievable concentrations. (Recall that the varying a policies correspond to the critical DSR trajectories needed to form the AR boundary.)... 

The two following batch structures are thus required to achieve all achievable points ... 

Had Sam, Alex, and Donald known about how to convert continuous reactors to batch, what optimal batch structures would be required to generate the BTX AR with... 

The optimal continuous reactors for the BTX system are described in Section 7.2.2. Hence, an equivalent optimal batch structure is then... 

The conversion of continuous reactor structures to batch structures was also described in this chapter, which is useful because the AR need only be determined once. In this way, determination of a candidate region for a given reaction system and feed point may potentially guide the construction of both continuous and batch reactor structures, via a single construction step. 

The recycling of material is an essential feature of most chemical processes. Therefore, it is necessary to consider the main factors which dictate the recycle structure of a process. We shall start by considering the function of process recycles and restrict consideration to continuous processes. Later the scope will be extended to include batch processes. 

In Sec. 4.4 the possibility of using batch rather than continuous operations in the flowsheet was discussed. At that time, our only interest was the recycle structure of the flowsheet. There the approach was first to synthesize a flowsheet based on continuous... 

In batch process optimization, one of the principal objectives is to improve equipment utilization through reduction in dead time. This requires both structural and parameter optimization, with many options available. 

MOPAC runs in batch mode using an ASCII input hie. The input hie format is easy to use. It consists of a molecular structure dehned either with Cartesian coordinates or a Z-matrix and keywords for the type of calculation. The program has a very versatile set of options for including molecular geometry and symmetry constraints. Version 6 and older have limits on the size of molecule that can be computed due to the use of hxed array sizes, which can be changed by recompiling the source code. This input format allows MOPAC to be run in conjunction with a batch job-queueing system. 

Especially for flexible batch applications, the batch logic must be properly structured in order to oe implemented and maintained in a reasonable manner. An underlying requirement is that the batch process equipment be properly structured. The following structure is appropriate for most batch production facilities. 

The primaiy oojective of the structured approach is to separate cleanly the following two aspects of the batch logic ... 

In structuring the logic for a flexible batch apphcation, the following organization permits produc t technology to be cleanly separated from process technology ... 

Usually the critical part of structuring batch logic is the definition of the phases. There are two ways to approach this ... 

Small batch retorts, heated electrically or hy combustion, are widely used as carburizing furnaces and are applicable also to chemic processes involving the heat treating of particulate sohds. These are mounted on a structural-steel base, complete with cyhnder, furnace, drive motor, burner, etc. Units are commercially av able in diameters from 0.24 to 1.25 m and lengths of 1 to 2 m. Continuous retorts with helical internal spirals are employed for metal-heat-treating purposes. Precise retention control is maintained in these operations. Standard diameters are 0.33, 0.5, and 0.67 m with effec tive lengths up... 

Batch versus continuous Flowsheet input-output structure Crystallizer and recycle considerations Separation systems specification Product drying Energy systems... 

This section illustrates how the techniques described in Chapter 4 can be used to develop a procedure for the job of the top floor operator in the batch plant considered earlier. Two techniques are illustrated (i) a hierarchical task analysis (HTA) of the job, and (ii) a predictive human error analysis (PHEA) of the operations involved. HTA provides a description of how the job is actually done while PHEA identifies critical errors which can have an impact on the system in terms of safety or quality. The basic structure of the procedure is derived from the HTA which specifies in increasing detail the goals to be achieved. To emphasize critical task steps, various warnings and cautions can be issued based on the likely errors and recovery points generated by the PHEA. 

Chemical development Proof of structure and configuration are required as part of the information on chemical development. The methods used at batch release should be validated to guarantee the identity and purity of the substance. It should be established whether a drug produced as a racemate is a true racemate or a conglomerate by investigating physical parameters such as melting point, solubility and crystal properties. The physicochemical properties of the drug substance should be characterized, e.g. crystallinity, polymorphism and rate of dissolution. 

Guidance on specifications is divided into universal tests/criteria which are considered generally applicable to all new substances/products and specific tests/criteria which may need to be addressed on a case-by-case basis when they have an impact on the quality for batch control. Tests are expected to follow the ICH guideline on analytical validation (Section 13.5.4). Identification of the drug substance is included in the universal category, and such a test must be able discriminate between compounds of closely related structure which are likely to be present. It is acknowledged here that optically active substances may need specific identification testing or performance of a chiral assay in addition to this requirement. 

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