Maintenance of product

The maintenance of product formation, after loss of direct contact between reactants by the interposition of a layer of product, requires the mobility of at least one component and rates are often controlled by diffusion of one or more reactant across the barrier constituted by the product layer. Reaction rates of such processes are characteristically strongly deceleratory since nucleation is effectively instantaneous and the rate of product formation is determined by bulk diffusion from one interface to another across a product zone of progressively increasing thickness. Rate measurements can be simplified by preparation of the reactant in a controlled geometric shape, such as pressing together flat discs at a common planar surface that then constitutes the initial reaction interface. Control by diffusion in one dimension results in obedience to the... 

Information that has been obtained from this pilot plant includes (1) alkylate quality at simulated commercial operating conditions, (2) alkylate yield, (3) isobutane consumption, (4) catalyst life, (5) maintenance of product quality with catalyst life, and (6) selectivity data (which contributes to the determination of reaction rate constants). 

A part of the analytical planning for a chemical complex is the setting up and maintenance of a sample library, where analyzed samples from each tank car load or reactor lot are stored for reference purposes. The retention time for these samples is set to exceed the probable delay between the time of product shipment and time of final consumption. Thus, if a customer is having difficulty with a particular batch of product, the retained samples enable the company to check the specifications and render rapid technical assistance. Reanalysis of the sample may also be used by the company to accept or reject claims regarding the quality of a product shipment. Thus, proportional process control, raw materials and product, analysis, sample retention, and careful record-keeping all comprise important parts of an operating chemical complex necessary for the maintenance of product quality and customer satisfaction. 

QC (the function responsible for the maintenance of product quality to the agreed standard). Standards must be documented to show the company s requirements for the consumer (individual, group and/or national regulatory) combined with the economic and efficient utilisation of resources. 

Data on the consistency of fermentation conditions and culture growth, and on the maintenance of product yield should be presented. Criteria for the rejection of culture lots should be established. The maximum number of cell doublings or passage levels to be permitted during production should be specified, based on information on the stability of the host-cell/vector system on serial subculture up to and beyond the level used in production. 

As the new clean fuels enter the marketplace, both refinery process control and maintenance of product quality during distribution are crucial. Availability of near real time sulfur data, particularly in downstream applications, can have significant value when time critical decisions must be made for a custody transfer and for detecting transport boundaries of similar fuel streams flowing throu a pipeline system. 

Stops and starts of the roasting workshop must be uncommon because in these cases, momentary pollution is higher compared to the international standards. Proper operation and regular maintenance of production facilities of the complex would prevent fluctuations in gaseous (gaseous wastes). Several research topics on environmental protection of Ghazaouet s city coifld be conducted in collaboration... 

Temperature control has the advantage of being fast, but it may not hold the product purity constant. Composition control is slow, but it will drive the product purity to the desired value. The next control structure studied is a cascade combination of composition and temperature control that achieves both fast control and the maintenance of product purity. 

Smooth and well-controlled operation of the plant with maintenance of product quality at desired productivity level with profitability. 

Maintenance of product quality through reduction of respiration rate, browning reactions, fruit softening, and decay,... 

Christer A.H., Wang W., Sharp J. and Baker R., (1998) A Case Study of Modelling Preventive Maintenance of Production Plant Using Subjective Data , Journal of the Operational Research Society, Vol. 49, pp. 210-219. 

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