Eggshell thickness

This level of deposition cannot be tolerated in any modem boiler design, irrespective of where in the world a boiler operates or the type of duty required. Even limiting the maximum acceptable thickness of boiler waterside deposition to an eggshell thickness standard, as once proposed by many people in the industry, is not satisfactory today. Indeed, under modem higher heat-flux density conditions, operators of industrial WT boilers working to this standard would have to contend with frequent disruptions because of mptured tubes or worse, while FT boilers might eventually suffer from a collapsed furnace and need to be written off. 

Extremely thin, glassy silicate scales of less than eggshell thickness may sufficiently insulate the tubes of WT boilers and the furnace tube of FT boilers for tube failure to occur through deformation and rupture. 

It was expected that an eggshell thickness of scale would form, but that it would be relatively soft and easily removed (despite normally containing some silicate and sulfate). However, a disadvantage of this method of internal control was that the carbonate degraded to form carbon dioxide, and at higher pressures the rate of breakdown was so great that the necessary carbonate reserve required to prevent sulfate scale often could not be maintained. (Never mind the danger to the steam and condensate lines from the production of carbon dioxide and ultimately carbonic acid.)... 

Assume a FT boiler of, say, 500 HP, having 2,500 sq ft of heat generating surfaces (and 225 sq ft of internal shell below the waterline, which becomes hot and to which scale can adhere). If we also assume that the boiler has a uniform deposit of scale and corrosion debris on all waterside surfaces to an eggshell thickness (31 mil), then the total mass of dirt equates to ... 

Ratcliffe, D.A. (1970). Changes attributable to pesticides in egg breakage frequency and eggshell thickness in British Birds. Journal of Applied Ecology 7, 67-107. 

Koivusaari J, Nuuja I, Palokangas R, Finnlund M. 1980. Relationships between productivity, eggshell thickness and pollutant contents of addled eggs in the population of white-tailed eagles Haliaetus albicilla L. in Finland during 1969-1978. Environ Pollut 23 41-52. 

No adverse effects on survival, egg laying, fertility, or eggshell thickness. Elevated residues (mg/kg dry weight) in humerus (13), tibia (62), and liver (2)... 

Haegele, M.A., R.K. Tucker, and R.H. Hudson. 1974. Effects of dietary mercury and lead on eggshell thickness in mallards. Bull. Environ. Contam. Toxicol. 8 5-11. 

Pattee, O.H. 1984. Eggshell thickness and reproduction in American kestrels exposed to chronic dietary lead. 

Food concentration normal with no overt adverse signs of TBTO exposure noted in adults. Decreased hatchability and increase in percent of chicks found dead in the shell were noted at 60 and 150 mg/kg food. Egg production and eggshell thickness normal. Abnormal blood chemistry and hepatic EROD noted in parent birds treated with TBTO (Coenen etal. 1992)... 

Blus, L.J., T.G. Lamont, and B.S. Neely, Jr. 1979. Effects of organochlorine residues on eggshell thickness, reproduction, and population status of brown pelicans (Pelecanus occidentalis) in South Carolina and Florida, 1969-76. Pestic. Monit. Jour. 12 172-184. 

Ohlendorf, H.M., E.E. Klaas, and T.E. Kaiser. 1979. Environmental Pollutants and Eggshell Thickness Anhingas and Wading Birds in the Eastern United States. U.S. Fish Wildl. Serv. Spec. Sci. Rep. — Wildl. 216. 94 pp. 

DDT is not highly toxic to birds when compared with fish. It is best known for the adverse effects on reproduction that is associated with the effects on eggshell thinning, especially DDE. Ratcliffe established the relationship between eggshell thickness and the widespread use of toxic... 

Fernie, K. J., Shutt, J. L., et al (2009) Environmentally relevant concentrations of DE-71 and HBCD alter eggshell thickness and reproductive success of American kestrels. Environmental Science and Technology, 43(6) 2124-2130. 

Table 11.5 Organochlorine residues in the eggs and changes in eggshell thickness index in 17...

Impregnated pellet region (average eggshell thickness or pellet diameter, mm) Characteristic diffusion 2.2 0.17 0.23 0.17 0.17... 

Fig. 28. Site density, pellet size, and eggshell thickness effects on FT synthesis selectivity (Co catalysts Si02, TiOi, and AI2O3 supports 473 K, H2/CO = 2.1, 2000 kPa, 50-62% CO conversion)., Dispersion/support effects , pellet size effects O, eggshell catalysts (Table VII) A, from Refs. 47 and 48.

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