Process selection drivers

As mentioned previously, selecting the right manufacturing process is not always simple and obvious. In most cases, there are several processes that can be used for a component, and selection depends on a large number of factors. Some of the main process selection drivers are shown in Figure 1.11. The intention is not to infer that these are necessarily of equal importance or occur in this fixed sequence. 

With reference to the manufacturing process PRIMA selection matrix in Figure 2.2, it can be seen that the requirement to process carbon steel in low to medium volumes (1000-10000) returns thirteen candidate processes. This is a large number of processes from which to select a frontrunner. However, some processes can be eliminated very quickly, for example, those that are on the border of economic viability for the production volume requested. The process of elimination is also aided by the consideration of several of the key process selection drivers (as shown in Figure 1.11) in parallel. For example ... 

Generally made up of representatives from several departments as well as select drivers, an accident review committee I offers several advantages to your decision-making process ... 

The principal suppliers of intensified unit operations increasingly realise that the ideal approach is driven by business requirements, although of course process drivers will retain an important place. Process drivers are those where the physical and chemical requirements of the process are determined and then used to select the equipment which best suits the process. Business drivers are financial issues relating to the operability and profitability of the process, and companies such as Protensive rightly see the massive business opportunities afforded by the radical PI approach. 

The second step in developing the process air train is selecting the air blower main driver. This step includes many alternatives such as power recovery expanders, steam turbines, and electric motors. The following example illustrates these alternatives. 

Historically, the most popular driver for the centrifugal compressor has been the steam turbine. Steam turbines can readily be speed matched to the compressor. Prior to the upsurge in energy costs, reliability, simplicity, and operational convenience were the primary factors in driver selection. The steam turbine, with its ability to operate over a relatively wide speed range, was ideal for the centrifugal compressor, which could be matched to the process load by speed modulation. 

One of the first questions the designer must answer concerns which type steam turbine should be used. The back pressure turbine is. selected when process steam demands are greater than the steam required for process drivers such as large compressors. This type turbine is also selected when various steam levels are required by the process. 

The condensing turbine is selected when steam demand for process drivers is greater than the low-pressure process steam requirements. It is also selected when no high pressure steam is available. 

The condensing steam turbine has a relatively low thermal efficiency because about two-thirds of the steam enthalpy is lost to cooling water in the condenser. Expensive boiler feedwater treatment is required to remove chlorides, salts, and silicates, which can be deposited on the blades causing premature failure. The blades are already under erosion conditions because of water drops present in the condensing steam. Even with these disadvantages, the condensing turbine is still selected, especially in a process that requires very large compressor drivers and relatively low amounts of process steam. 

The team should also look for the processes which select priorities for investment and management attention. Possible drivers for these are ... 

Many compressors are designed and operated at a fixed condition in a process or refrigeration cycle. However, at least an equal number are designed and operated over a varying, or at the initial selection unknown, set of conditions of suction or discharge pressures. This situation is a reality and an economical necessity if the full horsepower of the compressor and driver combination is to be realized. 

Torque requirements are a primary concern during the selection process. In all applications where variable or high torque is transmitted from the driver to the driven unit, a flexible coupling rated for the maximum torque requirement must be used. Rigid couplings are not designed to absorb variations in torque and should not be used. 

Innovation - advocates and opponents origin from microtechnology list of microfabrication techniques selectivity and efficiency as main driver for industrial implementation special properties and general advantages of micro reactors process-development issues BASF investigations on liquid/liquid and gas-phase reactions micro reactors as ideal measuring tools production in micro reactors as exception, the rule will be transfer to mm-sized channels [111],... 

Based on the selected flowcharts (process flow diagrams) one can make a first rough estimate of the costs of the new processes. Various standard methods for this are available, depending also on the company s systems for cost estimation. This part of Step 2 should not be forgotten, because it can clearly show the benefits of a new process in terms of costs, which is one of the main drivers for changes in processes. It also helps in ranking ideas. 

The input/output driver is also used for the (retro)synthetic tree inspection. The user can walk through the tree generated, inspect the selected nodes, edit them, and submit them for further processing by the SPS generator, thus creating new branches and levels of the (retro)synthetic tree. Each node of the (retrosynthetic trees stores not only the two-dimensional structure of the chemical compound, but also the distance from its father (i.e starting structure) measured by the reaction as well as chemical distances, and also its fragmentation level, measured by its order. 

Material Selection of appropriate material for examination is mainly determined by the time that has elapsed from administration of the toxic substance to collection of the material, as well as the site of conducting examinations (a clinical or forensic laboratory, or the site of the incident, for example, during a roadside check of a driver). Various compounds occur in various materials - parent, and active and inactive metabolites. Active metabolites influence life processes, and the presence of inactive metabolites in the organism could attest to consumption of a substance a long time ago. Currently available analytical techniques are applied to detect, identify and determine chemical substances in classical biological material (i.e. blood, urine and sections of internal organs) as well as in so-called alternative materials (i.e. hair, saliva and sweat). In recent years, numerous studies aimed at... 

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