Starting the Design Process

Start the design process by making simple block diagrams of the main components of the system. Then, make a pictorial diagram indicating the exact parts you plan to use. Along with the diagram and list of parts, include the parameters of each part as it relates to your system, supplier and contact information, and the cost of each part. 

Before we start the design process, we recall the general rule with regard to mass balances — namely, that only the streams crossing our chosen boundary are... 

Calculate the minimum component/system/region wall thickness for a single wall protection to obtain a reference point for starting the design process. 

Let us examine how one determines the values of the inductor and capacitor. Several assumptions have to be made at the beginning of the design process since several of the tank circuit s characteristics are variable within the application. The first is to assume a value for the Q of the tank circuit. In the application, the Q varies greatly with the amount of load placed on the output of the supply. So, a good value to start with is... 

It is furthermore iterative in the sense that one should start from a coarse model, which is then successively refined to the desired or possible depth. Failures in the models or problems of different types tested so far can be detected and treated at an early stage of the design process. 

Snapshots illustrate specific example situations. Figure 6.18 shows snapshots depicting the state of our spreadsheet before and after an operation. (The thicker lines and bold type represent the state after the operation.) Notice that because we are dealing with a requirements model here, we show no messages (function calls) between the objects they will be decided in the design process. Here we re concerned only with the effects of the operation invoked by the user. This is part of how the layering of decisions works in Catalysis We start with the effects of operations and then work out how they are implemented in terms of collaborations between objects. 

Chemical process design, as it is commonly known, typically starts with a general problem statement with respect to the chemical product that needs to be produced, its specifications that need to be matched, and the chemicals (raw materials) that may be used to produce it. Based on this information, a series of decisions and calculations are made at various stages of the design process to obtain first a conceptual process design, which is then further developed to obtain a final design, satisfying at the same time, a set of economic and process constraints. The important point to note here is that the identity of the chemical product and its desired qualities are known at the start but the process (flowsheet/operations) and its details are unknown. 

Use case specifications document functional requirements. The next step is to design the partial system that the current iteration is supposed to deliver. The gap between requirements and design is not trivial, and a bridge between the two is desired. This bridge is what object-oriented analysis is about. The domain analysis object model is not the final design. However, it provides a starting point for the design process. 

On the basis of this development afforded by Eastman and Halcon, in 1983 the Eastman Chemical Company (Kingsport, TN) started the commercial process for the manufacture of acetic anhydride (Figure 5). Methyl acetate, the feedstock for the carbonylation reaction, was produced in a separate esterification step from acetic acid and methanol. The process was designed to produce 225 000 tons of acetic anhydride and 75 000 tons of acetic acid/year. The overall yield of acetic anhydride based on methanol is approximately 96 % [2, 47]. 

Loss-of-Containment Causes The list in Table 23-30 indicates four basic ways in which containment can be lost. These cause categories can be used both as a checklist of considerations during the design process and as a starting point for evaluating the adequacy of safeguards as part of a process hazard and risk analysis. 

---