Selective process development

LCA can also be applied to chemical processes, with a view to process comparison and selection, process development or process synthesis. LCA can likewise... 

A derivative of the Claus process is the Recycle Selectox process, developed by Parsons and Unocal and Hcensed through UOP. Once-Thm Selectox is suitable for very lean acid gas streams (1—5 mol % hydrogen sulfide), which cannot be effectively processed in a Claus unit. As shown in Figure 9, the process is similar to a standard Claus plant, except that the thermal combustor and waste heat boiler have been replaced with a catalytic reactor. The Selectox catalyst promotes the selective oxidation of hydrogen sulfide to sulfur dioxide, ie, hydrocarbons in the feed are not oxidized. These plants typically employ two Claus catalytic stages downstream of the Selectox reactor, to achieve an overall sulfur recovery of 90—95%. 

The data most frequentiy collected and reported in catalyst performance evaluations are activity or turnover number, selectivity to the desired product(s), overall yield, catalyst life, and the identities and yields of by-products produced. These data are used to further catalyst or process development research efforts, to monitor catalyst manufacture, and to provide quaUty assurance information to catalyst users. 

Any program developed in-house must be easy to use, or user-friendly. If the program has various options for input, analysis, computation, and output, then it must provide the user with a fast way to select them. To meet this need, the system is likely to be menu-driven. The peripheral interactive devices such as mice, joysticks, light pens, graphic tablets, and templates are helpful and often used to expedite the selection process. 

Assistance in problem definition and in developing a test program should be sought from persons experienced in the field. If your organization has a consultant in separations of this land, by all means m e use of the expertise available. If not, it may be wise to employ an outside consultant, whose special knowledge and guidance can save time, money, and headaches. It is important to do this early after the separation equipment has been installed, there is httle a consultant can do to remedy the sometimes disastrous effects of a poor selection. Often it is best to work with established equipment manufacturers throughout the selection process, unless the problem is unusually sensitive or confidential. Their experience with problems similar to yours may be most helpful and avoid many false starts. 

In certain cases, it is necessary to choose materials for equipment to be used in a process developed in the laboratory and not yet in operation on a plant scale. Under such circumstances, it is obviously impossible to make plant tests. A good procedure in such cases is to construct a pilot plant, using either the cheapest materials available or some other materials selected on the basis of past experience or of laboratory tests. While the pilot plant is being operated to check on the process itself, specimens can be exposed in the operating equipment as a guide to the choice of materials for the large-scale plant or as a means of confirming the suitability of the materials chosen for the pilot plant. 

In this phase of the toller selection process, we assume the long list became a short list and now one or more candidate tollers from the short list will be given an opportunity to prepare a commercial bid. This by no means indicates the short listed tollers are perfect. There may be deficiencies that need to be corrected in concert with the client. With proper effort, one will be successful and be engaged for the toll. Sometimes it is appropriate to decide on a backup toller, as complications can develop that prevent the primary candidate from executing the project as originally planned, due to an incident in their plant, departure of key personnel, or unexpected production demands on the toller. 

It is incumbent upon the toller to develop and follow internal management systems as appropriate to support business needs, production needs, process safety, environmental responsibility, and worker health. The selection process should have considered whether or not satisfactory systems are in place. Nevertheless, the contract or auxiliary documents may be the vehicle used to help ensure that the system reviewed is the system actually used for completing the toll in question. Within the process safety management system, the management of change and training elements are essential subsystems. 

As discussed in Chapter 2, The Toller Selection Process, evaluating the site s safe work practice procedures should have been a part of the review during the toller selection process. Still, new materials may indicate a need to revise or develop special procedures to address unique chemical and physical hazards. New hazards such as vacuum, ciyogenics, ultra-high pressure, or new rotating equipment could be introduced. Medical monitoring requirements or special handling and spill response procedures for the toll s raw materials and products may indicate a need to write or revise safe work practices. 

Pre-contractual To establish conditions during qualification and contract development for the purposes discussed in Chapter 2, The Toller Selection Process. 

After each issue outlined in the evaluation criteria has been developed for each corrective measure, the selection of the most appropriate alternative can be made. Trade-offs among health risks, environmental effects and other pertinent technical, environmental and human health factors enter into this decisionmaking process. In the RCRA context, cost is not a factor in the selection process except when two or more corrective measure alternatives are determined by EPA to provide similarly adequate levels of protection of human health and the environment. 

A critical consideration with UF technology is the problem of fouling. Foulants interfere with UF by reducing product rates- sometimes drastically-and altering membrane selectivity. The story of a successful UF application is in many respects the story of how fouling was successfully controlled. Fouling must be considered at every step of UF process development in order to achieve success. 

You need to develop documented procedures that define your subcontractor evaluation and selection process and in certain cases this may result in several closely-related procedures for use when certain conditions apply. Do not try to force every purchase through the same selection process. Having purchasing policies that require three quotations for every purchase regardless of past performance of the current subcontractor is placing price before quality. Provide flexibility so that the policies and procedures complexity match the risks anticipated. Going out to tender for a few standard nuts and bolts would seem unwise. Likewise, placing an order for lm of equipment based solely on the results of a third party ISO 9000 certification would also seem unwise. 

Although the source of raw materials may not be at the plant site, it is an e.xtremcly important factor in the ultimate location of the plant. Process development work and economic studies will indicate the minimum standards for raw materials selection. When these standards have been determined, all possible sources of acceptable raw materials can be located and a detailed analysis can proceed. 

Other detrimental factors which should to be taken into account in the materials selection process include temperature cycling and the presence of halide gases. Specialist alloys containing rare earth element additions such as cerium, lanthanum and yttrium have been developed for use in certain environments up to 130°C. 

Key lessons learned so far in the process, other than the amount of time and work required to develop an ELN system for 2500 scientists at 10 sites in 5 countries across 3 continents, are that setting out the success criteria up front allowed for a very focused selection process. Also, engaging a broad... 

A prototype system implemented with the Formulogic shell has recently been reported by Pfizer [21]. The system has been designed to use preformulation data on new drugs and recommend early development formulations, predict product properties, and select processing conditions suitable for scale-up. 

A major challenge will be to develop new processes or step-up technologies that increase the yield and/or selectivity, use cheaper raw materials, decrease energy consumption, minimize the product separation and purification needs and lower capital investment. Iimoyative step-out technologies can still have a major impact on existing processes. An excellent example of such an accomplishment is the reactive distillation process developed by Eastman Chemicals for production of methyl acetate by via the reaction [2]... 

Process development for the selective hydrogenolysis of CCI2F2 (CFC-12) into CH2F2 (HFC-32)... 

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