Processing modification

Linnhoff, B., and Parker, S. J., Heat Exchanger Network with Process Modifications, IChemE Annual Research Meeting, Bath, U.K., April 1984. 

Figure 14.9 The composite curves after process modifications shows a much reduced energy target. (From Smith and Linnhoff, Trans. IChemE, ChERD, 66 195, 1988 reproduced by permission of the Institution of Chemical Engineers )...

Developments. A variety of process modifications aimed at improving surface finish or weld line integrity have been described. They include gas assisted, co-injection, fusible core, multiple Hve feed, and push—pull injection mol ding (46,47). An important development includes computer-aided design (CAD) methods, wherein a proposed mold design is simulated by a computer and the melt flow through it is analy2ed (48). 

Research Trends. Research since the late 1970s appears to have centered on further process modifications and optimization of conventional processes, reduction in pollution, evaluation of potentially more efficient processing technology, increased use of less expensive softwood sources to extend the available hardwood suppHes, and accommodation of recycled newspaper pulp (see Recycling, paper). 

In-Plant Waste Control. Pollution can be reduced or eliminated by process modification, chemical and raw materials substitution, or recovery of by-products. In addition, process modification generally increases product yield by incorporating control devices. 

Giaphite with its exceptional strength and thermal stabiUty at high temperatures is a prime candidate material for many aerospace and nuclear appHcations. Its properties, through process modifications, are tailorable to meet an array of design criteria for survival under extremely harsh environmental operations. 

A future goal for the integration of graphics and process design simulators is to be able to use an interactive graphics program to prepare the input to the process simulator. This capabiHty would allow tme on-line process modification, flow-sheet optimization, and process optimization, and is likely to be one of the key developments in this field in the 1990s (99). 

Environmental factors should also be incorporated into a company s technical or research and development program. Since the planning horizons for new projects may now extend to 5 to 10 years, R D programs can be designed for ecific projects. These may include new process modifications or end-of-pipe control technologies. 

Control of Plant and Process Modifications Many accidents have occurred because plant or process modifications had unforeseen and unsafe side effects (Sanders, Management of Change in Chemical Plants Learning from Ca.se Histories, Butterworth-Heinemann, 1993). No such modifications shoiild therefore be made until they have been authorized by a professionally quahfied person who has made a systematic attempt to identify and assess the consequences of the proposal, by hazard and operability study or a similar technique. When the modification is complete, the person who authorized it... 

Conduct thorough evaluation of process modification using management of change review procedure... 

Do Not Require Process Modifications iv. Thermal swing adsorption V. Pressure swing adsorption... 

Measures to control welding fume include process modifications, engineering controls, system of work and administrative acdon as summarized in Figure 5.5. 

Group 2 includes long-term reduction measures involving process modifications or process substitutions to eliminate problem wastes. This second group of corrective actions fall into two investment categories - moderate and high. Such projects... 

Information provided in Part III. Section 8. of Form R is optional. In this section, you may identify waste minimization efforts relating to the reported toxic chemical. Waste minimization reduces the amount of the toxic chemicai in wastes by reducing waste generation or by recycling. This can be accomplished by equipment changes, process modifications, product reformulation, chemical substitutions, or other techniques. Waste minimization refers exclusively to practices which prevent the generation of wastes. Treatment or disposal does not minimize waste and should not be reported In this section. Recycling or reuse of a toxic chemical is considered waste minimization. Waste minimization applies to air emissions and wastewater, as well as to liquid or solid mate-... 

GLC s effected by plant process modifications, i.e. emission quantities, velocities and temperatures. 

Burch, W. M. (1986). Process Modifications and New Chemicals. Chemical Engineering Progress (April), 5-8. 

Startup following a process modification or after an emergency shutdown... 

Local ventilation systems (see Fig. 2.2) are used for local controlled zones. These systems are air technological methods for local protection. Primarily, local protection should be made using process methods such as encapsulation or process modification (see Design Methodology, Chapter 3). Another use for local ventilation systems is source capturing. 

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). 

The introduction of the efficient agitation system was a process modification (see Section 2.6), but its consequences were not foreseen. 

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