Babcock & Wilcox Company.

ABSTRACT:
Millions of tons of hazardous wastes are produced each year in the United States. Of these wastes, some are recycled or destroyed, while others are stored for subsequent disposal. The stored wastes are a hazard due to their potential for discharge into the environment. For many toxic organic wastes, detoxification using solar energy is a liable means for eliminating the environmental risks. In addition, it offers the potential for being more efficient and cost effective than the currently preferred method of disposal, incineration using fossil fuels. This Phase 1 program provides an approach to the destruction of hazardous industrial wastes using solar energy. The approach makes use of both the photoreduction energy and thermal aspects of solar energy to destroy highly toxic hazardous wastes. This ultraviolet (UV) light energy is available in addition to the thermal energy in the detoxification process. The Phase 1 program has established poly-chlorinated biphenyls (PCB's) as the candidate material for the detoxification process due to their highly toxic nature and the large quantities which require disposal. The chlorine-carbon bonds that exist is PCBs are susceptible to photolytic reduction from intense solar flux in the UV range. During Phase 1, the feasibility of the concept was verified through an extensive literature search on photochemical effects. This search identified that the combined aspects of concentrated solar energy, photoreduction and thermal, could supply the required detoxification. Solar test facilities were also evaluated during this phase. In addition, candidate test materials were determined for a test burn using a photolytic detoxifier concept also established during Phase 1. For the Phase 1 workscope the Babcock & Wilcox Company assembled a team including Veda, Inc. and Woodward-Clyde Consultants. This team provided the project with a broad and diverse experience base in hazardous waste ~ destruction, chemical and environmental engineering, -optical analysis, and design and fabrication of solar thermal plant components and systems.… (altro)

ABSTRACT:
The Department of Energy has embarked on an extensive program to use solar energy to replace fossil fuel. One expanding effort is directed toward generating electric power with solar energy. Stand-alone plants utilizing thermal storage systems when solar is unavailable represents one facet of the program. Another facet involves demonstration and first-generation plants which "repower" present gas- and oil-fired fossil plants with solar energy for both industrial and utility boilers. The steam/water solar steam generators represent the best chance for early demonstration projects, although they have recognized shortcomings in the areas of thermal storage and steam-side pressure drop. Systems with either sodium or fused salts as their heat transfer medium have a greater potential for future development of stand-alone plants. Babcock & Wilcox, as a supplier of fossil and nuclear steam generators, has been involved in several solar power projects including both water/steam and sodium systems. The paper describes such solar power generation systems.… (altro)

ABSTRACT:
For high reliability all high pressure drum type boilers must avoid DNB under all operating conditions with a sufficient margin of reserve for upset transients. DNB is a localized phenomenon caused by a critical combination of operation parameters which include pressure, heat flux, steam quality, and mass velocity.

The overall circulation ratio often used in the power industry to compare and evaluate the safety of circulation systems is not a pertinent criterion, since it lumps together the flows of the most exposed circuits with those of low duty. Even with high circulation ratios, drum type boilers with smooth tubes may have circuits that operate during upsets close to the combinations of parameters that produce DNB.

The B&W design with ribbed tubes, however, provides high natural circulation flow rates (even at pressures approaching the critical pressure) that maintain significant margins of safety during adverse upsets. Thus, with the use of ribbed tubes, it is possible to meet utility requirements for natural circulation boilers of any size for 2900 psig drum operating pressure, that have high availability and no auxiliary power demand.… (altro)