Task integration

Furedy JJ, Algan O, et al (1999) Sexually dimorphic effect of an acute smoking manipulation on skin resistance but not on heart-rate during a cognitive verbal task. Integr Physiol Behav Sd 34(4) 219-226... 

The AIDES program definitely has its limitations. The internal representation of solution thermodynamics is simplistic it cannot, for example, handle azeotropes. Also, the species allocation, once proposed, is adhered to too rigidly and its task integration capabihty is somewhat weak. In industrial situations, its performance is judged to be good, but only slightly better than conceptual designers that resolve property differences directly in terms of common unit operations. 

Keep task identification distinct from task integration and equipment design. Think carefully about what needs to be accomplished (tasks), then consider how it will be accomplished (equipment). In other words, remember the architect s maxim, Form follows function. ... 

If the hierarchical means-ends analysis synthesis procedure is applied to the methyl acetate problem, the task identification, task integration, and equipment design stages are kept completely separate. Following the property-difference hierarchy, an identity-changing reaction task (Task A) is identified first, as before. When examining the differences between the result of this reaction task application and the product methyl acetate and by-product water destinations,... 

Heat integration, or the synthesis of heat-exchanger networks, is a classic problem of integrating complementary tasks at the task integration stage of the... 

Since these are the building blocks of nearly all chemical processes, it is common to create flowsheets involving these basic operations as a flrst step in process synthesis. Then, in a task integration step, operations are combined where feasible. In the remainder of this section, before considering the steps in process synthesis, each of the basic operations is considered in some detail. 

As for the pressure levels in the reaction operations, 1.5 atm is selected for the chlorination reaction to prevent the leakage of air into the reactor to be installed in the task integration step. At atmospheric pressure, air might leak into the reactor and build up in sufficiently large concentrations to exceed the flammability limit. For the pyrolysis operation, 26 atm is recommended by the B.F. Goodrich patent (1963) without any justification. Since the reaction is irreversible, the elevated pressure does not adversely affect the conversion. Most likely, the patent recommends this pressure to increase the rate of reaction and, thus, reduce the size of the pyrolysis furnace, although the tube walls must be thick and many precautions are necessary for operation at elevated pressures. The pressure level is also an important consideration in selecting the separation operations, as will be discussed in the next synthesis step. 

At the completion of step 4, each of the candidate flowsheets has a complete set of operations that eliminates the differences between the raw materials and products. Still, with the exception of the distillation operations, specific equipment items are not shown. The selection of the processing units, often referred to as unit operations, in which one or more of the basic operations are carried out, is known as task integration. To assist in this selection, the reader is referred to Chemical Process Equipment (Walas, 1988). 

Figure 3.8 Flowsheet showing task integration for the vinyl-chloiide process.

This completes the task integration in Figure 3.8. Can you suggest ways to reduce the need for fuel and hot utilities such as steam ... 

Figure 3.16 Flowsheet showing a task integration for the tPA process.

The next synthesis step involves task integration, that is, the combination of operations into process units. In one task integration, shown in Figure 4.20, reactor effluent is quenched rapidly to 1,150 F, primarily to avoid the need for a costly high-temperature heat exchanger, and is sent to a feed/product heat exchanger. There, it is cooled as it heats the mixture of feed and recycle chemicals to 1,(X)0°F. The stream is cooled further to 100°F, the temperature of the flash separator. The liquid from the quench is the product of the reactor section, yet a portion of it is... 

Task integration (to combine operations into unit processes)... 

The RD s mthesis of methyl acetate by Eastman Chemicals is considered to be the textbook example of a task integration-based process s3mthesis (Stankiewicz and Moulijn, 2002 Stankiewicz, 2003, 2001 Li and Kraslawski, 2004 Siirola, 1996a) (see figure 1.1). 

Figure 1.1. Schematic representation of the conventional process for the synthesis of methyl acetate (left) and the highly task-integrated RD unit (right). Legend ROl reactor SOI splitter S02 extractive distillation SOS solvent recovery S04 MeOH recovery SOS extractor S06 azeotropic column S07,S09 flash columns SOS color column VOl decanter...

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