Primary operational problems

Primary operational problem—term for the first issue (problem) that created a process upset. 

Both friction and wear measurements have been used to study boundary lubrication of fuel because sticking fuel controls and pump failures are primary field problems in gas turbine operation. An extensive research program of the Coordinating Research Council has produced a baH-on-cylinder lubricity test (BOCLE), standardized as ASTM D5001, which is used to qualify additives, to investigate fuels, and to assist pump manufacturers (21). 

Miscibility with the Feed Components. In a solute—solvent system exhibiting strong positive deviations from Raoult s Law, the solute has only limited solubility in the solvent. Above a certain solute concentration, two liquid phases are formed. The presence of two liquid phases on the plates of a distillation column leads to instability and operational problems. It is therefore necessary to ensure that the solute concentration in the liquid phase never exceeds its solubility limit. This solubility limit gives a minimum feasible solvent concentration in the section below the solvent addition plate of the primary column. 

Wastewater treatment systems can be classified, in addition to pretreatment, as preliminary, primary, secondary, and tertiary (advanced) treatments. Pretreatment of industrial wastewater is required to prevent adverse effects on the municipal wastewater treatment plants. Preliminary treatment is considered as any physical or chemical process that precedes primary treatment. The preliminary treatment processes may consist of influent screening and grit removal. Its function is mainly to protect subsequent treatment units and to minimize operational problems. Primary treatment is defined as the physical or chemical treatment for the removal of settleable and floatable materials. The screened, degritted raw wastewater from preliminary treatment flows to the primary clarification tanks, which are part of the primary treatment facilities. Secondary wastewater treatment is the process that uses biological and chemical treatment to accomplish substantial removal of dissolved organics and colloidal materials. The secondary treatment facilities may be comprised of biological reactor and secondary clarification basins. Tertiary (advanced) wastewater treatment is used to achieve pollutant reductions by methods other than those used in primary and secondary treatments. The objective of tertiary wastewater treatment is to improve the overall removal of suspended solids, organic matter, dissolved solids, toxic substances, and nutrients. 

The primary motivation for predicting the electrochemical properties of the coolant circuits of water-cooled nuclear power reactors has been that of explaining and predicting tenacious operating problems that include SCC and CF, mass transport of corrosion products and subsequent fouling of heat transfer surfaces, activity transport due to the movement of neutron-activated radionuclides from the core to out-of-core surfaces that are not shielded, and, in the case of PWRs, the axial offset anomaly (AOA). This latter phenomenon results from the deposition of boron... 

Environmental Considerations Environmental considerations are continuing to be an increasingly important aspect of dryer design and operation as environmental regulations are tightened. The primary environmental problems associated with drying are particulate and volatile organic compound (VOC) emissions. Noise can be an issue with certain dryer types. 

Primary design problems, foaming, installation mishaps, relief problems, and tray and downcomer layout problems make up the rest of the column malfunctions. Familiarity with these problems is useful to troubleshooters and operation personnel, but only one incident out of every four is likely to be caused by one of these factors. All these topics, except the primary design, are relatively narrow and are treated accordingly in this book. 

Dioxin monitoring and abatement In order to allow the full implementation of primary measures for dioxin prevention, there is a need for a better understanding of the contribution of the process parameters to the formation of dioxins. This requires the monitoring of dioxin emissions for various installations and under varying conditions. Additionally, there is a need for research on the use and effectiveness of secondary measures in the foundry industry. Secondary measures (e.g. additive injection, catalytic filter bags) have been implemented in other sectors (e.g. steel, waste incineration, non-ferrous metals production), but there is very little experience of their performance and of possible operational problems which may occur in applying then in foundries... 

Early attempts at automatic ash removal in controlled air incinerators employed a bomb bay door concept. With these systems, the bottom of the primary chamber would swing open to drop ashes into a container or vehicle located below. Serious operating problems led to the discontinuance of these systems. More recent automatic ash removal systems use rams or plungers to push a mass of residue through the primary chamber and out a discharge door on a batch basis. Most of these systems have had only limited success. 

---