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1. Chapter 4: Selection By: Associate Professor Ts Dr Ruzinah Isha College of Engineering Universiti Malaysia Pahang

2. Process selection Definition: The development of the process necessary to produce the designed product

3. Process selection type Process types can be Project process – make a one-at-a-time product exactly to customer specifications Batch process – small quantities of product in groups or batches based on customer orders or specifications Line process – large quantities of a standard product Continous process – very high volumes of a fully standard product Process types exist on a continuum

4. Underlying process relationship between volume and standardization continuum

5. Process selection consideration 5 considerations Type of process; range from intermittent to repetitive or continuous Degree of vertical integration Flexibility or resources Mix between capital & human resources Degree of customer contact

6. Process performance metrics Definition: measurement of different process characteristics that tell us how process is performing Determining if a process is functioning properly as required Determination requires measuring performance

7. Process performance metrics

8. Linking of product design & Process selection Product design and process selection is directly link Type of product selected defines type of operation required Type of operation available defines broader organizational aspects such as Equipment required Facility arrangement Organizational structure

9. Linking design & process selection

10. Chemical product selection Selection using thermodynamics How much energy required Endothermic vs exothermic Energy integration Selection using kinetics Reaction path Best synthesis route Less objective criteria Risk in product selection MSDS

11. Process design New products are not realities until they are manufactured Process design is necessary to manufacture new product Process design means the complete delineation and description of specific steps in the production process and linkage among the steps that will enable the production system to produce products systems of desired quality, in the required quantity.

12. Steps in industrial Chemical product design

13. 5 steps of chemical product design There are 5 steps of product design to consider. Concept stage Opportunity assessment Customer requirements Technical requirements Critical-to-quality variables Superior product concepts Feasibility study Build product prototype Develop and evaluate performance testing methods Preliminary evaluation with select customers Develop process design

14. 5 steps of chemical product design Development stage Detailed design, equipment sizing and profitability analysis and optimization Develop start-up strategies Safety analysis Manufacturing stage Detailed plant design Construction Startup Operation Product-introduction stage Pricing Advertising Product literature Introduction to customers

15. Selection of chemical process design Step 1 – Batch vs continuous process Step 2 – The input/output structure Step 3 – The recycle structure Step 4 – General structure of separation process Step 5 – Heat exchanger network or Process energy recovery system

16. Smaller throughput/production amount Special product that required certification eg FDA Limited feedstock availability Seasonal product demand Slow reaction rate Prone to equipment fouling Choose Batch system if: Advantage batch Multiple operation equipment eg CSTR to Mixer Easy modify Disadvantage batch Strict schedule and controllability High operating labour cost Higher exposure to chemical

17. Economical for large throughput/production amount Fixed production rate/sale/demand. Equipment is optimally designed More efficient for throughput increment Choose continuous system if: Advantage Lower labor cost Excellent safety records & procedure Easy to control Flexible operation Disadvantage Large quantities of off-spec product Continuous operation throughout years Fouling tendency. Overcome: need parallel equipment design

18. Selection is based on Economical, chemical components & reactions involve Relate to legal, environmental and social responsibility Low waste, utility, energy requirement, risks and cost High yield, high safety and high profitability Sustainable Preferred condition P~ 1-10 bar, T <400 C. Others need to justify Chemical Process design selection of input and output

19. SUPPLYING MISSING INFORMATION Product details – require R&D. Up to this point we tried to minimise the work at each stage: simplified calculations, experiments kept to a minimum. This streamlines product design, allow easy comparisons between ideas and minimize time to market . We must confirm experimentally any information used already and fill in many gaps in our knowledge. One form of missing information, commonly required for the design of chemicals, is a synthetic pathway for the active molecules . Identified active species but in small quantities. We are less likely to have identified a satisfactory commercial route. Many of the techniques of chemistry will be valuable; one which is worth further discussion is a systematic way of developing a range of reaction path strategies for the active molecule.

20. SUPPLYING MISSING INFORMATION REACTION PATH STRATEGIES One of the first things chemists, biochemists, or pharmacists are likely to do when considering solutions to a product problem is to start to think of possible molecules required for synthesis. We discussed how combinatorial chemistry and natural product screening can assist in this process of generating ideas for active chemical species. The molecules identified are unlikely to be readily available and usually will be complex. How can we make them? Going backward from the target molecule to simple precursors is exactly what “the disconnection approach" to organic synthesis is designed to achieve.

21. SUPPLYING MISSING INFORMATION This approach, outlined by Stuart Warren, makes successive "disconnections" to reduce the target molecule to simple, available precursors. Each disconnection involves imagining breaking the structure of the target molecule ; this breakage is the inverse of a synthetic step. A disconnection should be related to a well-established synthetic method to go in the opposite direction and so will be closely connected with the functional groups available in the target molecule.

22. SUPPLYING MISSING INFORMATION Usually several different disconnections will be possible for any target molecule and many successive disconnections are likely to be necessary before simple precursors are reached. Thus many alternative synthetic routes can easily result from moderately complex molecules. An experienced organic chemist will usually be able to eliminate most of them immediately as completely impractical, leaving perhaps a handful of reasonable alternatives. Sometimes, none of the potential synthetic routes will look viable. In this case the suggested target molecule can be ruled out as a useful idea; it may be highly efficacious, but if it cannot be commercially made it will be of no use as our product. Alternatively, perhaps, it could be extracted from a natural product or made via fermentation. To illustrate the type of approach required to fill in the gaps in our information, we will give three examples.

23. EXAMPLE Example: synthesis of the tranquilizer, phenoglycodol The structure of this species is given in the upper left-hand corner of Figure 5.2-1. Suggest several routes by which it may be synthesized. SOLUTION This is a fairly complex molecule and so many pathways are possible. The most obvious, also shown in Figure 5.2-1, use commercially available precursors. Which synthetic route we prefer will depend on other factors, such as cost, safety , and so on.

24. EXAMPLE Example ; sterically hindered amines for CO 2 removal from gases Acid gas removal from gas streams (sweetening) is a very common process in the chemical and refining industries. For example, in a hydrogen plant, methane is converted by steam reforming to hydrogen and CO 2 . The CO 2 must then be removed to leave a pure product. In an existing plant, this CO 2 removal is often the bottleneck for capacity expansion. For this reason, your company would like to improve CO 2 removal from gas streams. How can you do so?

25. The end