Temporary modifications

As introduced in Section 14.2, bottlenecks in the process facilities can occur at many stages in a producing field life cycle. A process facility bottleneck is caused when any piece of equipment becomes overloaded and restricts throughput. In the early years of a development, production will often be restricted by the capacity of the processing facility to treat hydrocarbons. If the reservoir is performing better than expected it may pay to increase plant capacity. If, however, it is just a temporary production peak such a modification may not be worthwhile. 

When the modification is temporary. Twenty-eight people were killed by the temporaiy modification at Flixborough, one of the most famous of all time (Lees, Lo.s.s Prevention in the Proce.s.s Indwstrie.s, 2d ed., Buttei woi th-Heinemann, 1996 p. 2). 

Principal Option for Containment/ Recovery Excavation Vacuum extraction Temporary cap/cover Hydraulic modification No action Groundwater pumping Subsurface drains Hydraulic barriers Low permeability barriers No action Overflow/underflow containment (i.e. oil booms) Run off/run on control Diversion/collection No action Capping/ nsulation Operations modifications Gas collection/removal No action... 

One of the reactors developed a crack and had to be removed. (The crack was the result of a process modification see Section 2.6 b.) It was replaced by a temporary 20-in. pipe, which had two bends in it, to allow for the difference in height. The existing bellows were left in position at both ends of the temporary pipe (Figure 2-5). 

In 1985, Uie Cimadian Chemical Producers Association (CCPA) released a pampWet entitled, "Essential Components of Safety Assessment Systems . Modifications to process or plant was one of the topics discussed in Uiis pamplilet. CCPA recommended a 12 element program (listed below) to formally e.xamine and approve process conditions whellier permanent or temporary prior to implementation. 

The conceptual complement to the chiral modification of the catalyst is the temporary modification of the substrate. Unlike the chiral auxiliary strategy, temporary substrate modification has greater latitude in introducing the kind of groups... 

Nowadays, a strategic area of research is the development of polymers based on carbohydrates due to the worldwide focus on sustainable materials. Since the necessary multi-step synthesis of carbohydrate-based polymers is not economical for the production of commodity plastics, functionalization of synthetic polymers by carbohydrates has become a current subject of research. This aims to prepare new bioactive and biocompatible polymers capable of exerting a temporary therapeutic function. The large variety of methods of anchoring carbohydrates onto polymers as well as the current and potential applications of the functionalized polymers has been discussed recently in a critical review [171]. Of importance is that such modification renders not only functionality but also biodegradability to the synthetic polymers. 

Unnecessary derivatization (use of blocking groups, protection/de-protection, and temporary modification of physical/chemical processes) should be minimized or avoided if possible, because such steps require additional reagents and can generate waste. 

When the modification is temporary. Twenty-eight people were killed by the temporary modification at Flixborough, one of the... 

Control of fiber friction is essential to the processing of fibers, and it is sometimes desirable to modify fiber surfaces for particular end-uses. Most fiber friction modifications are accomplished by coating the fibers with lubricants or finishes. In most cases, these are temporary treatments that are removed in final processing steps before sale of the finished good. In some cases, a more permanent treatment is desired, and chemical reactions are performed to attach different species to the fiber surface, e.g. siliconized slick finishes or rubber adhesion promoters. Polyester s lack of chemical bonding sites can be modified by surface treatments that generate free radicals, such as with corrosive chemicals (e.g. acrylic acid) or by ionic bombardment with plasma treatments. The broken molecular bonds produce more polar sites, thus providing increased surface wettability and reactivity. 

The management system for reviewing, approving, and managing changes to process equipment was inadequate and needed substantial improvement. Temporary modifications were not reviewed by the appropriate technical discipline. 

A greater understanding of the MM2 program is needed to implement the new -2 option for the dihedral driver. In MM2, a temporary file stores the coordinates at the end of each optimization for use as starting positions for the next optimization. The procedures that create these files had to be changed. An alternative to modification of MM2, used previously (3.), was to create separate input files for each ( ), P conformation of interest. This allowed use of the standard driver with a 0 increment size. Special programs could be used to prepare all of the input files. The check of... 

Urmecessary derivatization (blocking group, protection, and deprotection, temporary modification of physical and chemical processes) should be avoided whenever possible. 

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