Chrome free organic tannages and molecular level understanding of the tanning process for the production of leather with high hydrothermal stability Samir DasGupta , New Zealand Leather and Shoe Research Association
It is rather strange that today I am talking about chrome-free tannages when I have devoted my whole life to improving the chrome-tanning system. When I was a student, I wondered why chrome tanned leather that stood the boil, did so only for about 1 to 2 minutes. My ambition was to find out how leather could be treated like textile, and we discovered and patented a product and process for improving the hydrothermal stability of chrome-tanned leather. This patent showed how chrome tanned leather could be boiled like textile for an hour without area loss. At LASRA we have also developed LASRA ThruBlu and modified ThruBlu processes to minimise the environmental impact of chrome tanning.
Evidence of Cr(VI) formation during analysis of leather Proposal of an alternative method of analysis through the ion-chromatographic approach and post-column reaction.
The formation of Cr(VI) in Cr(III) tanned leather, in neutral and alkaline solution, has been demonstrated by means of crossed experiments using different pH buffers, ethylenediaminetetraacetic acid as Cr(III) complexing agent and NaCl solutions. According to the found results the composition of the extracting solution suitable to extract Cr(VI) amount present in leather was pH 4.4 (which is also the tanned leather natural pH) and 5% NaCl (w/v). Interferences coming from coloured compounds have been eliminated with suitable SPE cartridges. A new protocol for the analysis of Cr(VI) based on ion chromatography and a diphenylcarbazide post-column reaction has been implemented. The use of a large volume injection loop (500mul) allowed to obtain a very low quantification limit (0.15mgkg(-1)) despite the low amount of leather extracted (0.2g with respect to 2.0g used by the IUC 18 official method). Evidence of the transient nature of Cr(VI) in leather requires using the external calibration procedure for the correct quantification of the species.
Turbine blade temperature calculation and life estimation - a sensitivity analysis
Abstract The overall operating cost of the modern gas turbines is greatly influenced by the durability of hot section components operating at high temperatures. In turbine operating conditions, some defects may occur which can decrease hot section life. In the present paper, methods used for calculating blade temperature and life are demonstrated and validated. Using these methods, a set of sensitivity analyses on the parameters affecting temperature and life of a high pressure, high temperature turbine first stage blade is carried out. Investigated uncertainties are: (1) blade coating thickness, (2) coolant inlet pressure and temperature (as a result of secondary air system), and (3) gas turbine load variation. Results show that increasing thermal barrier coating thickness by 3 times, leads to rise in the blade life by 9 times. In addition, considering inlet cooling temperature and pressure, deviation in temperature has greater effect on blade life. One of the interesting points that can be realized from the results is that 300 hours operation at 70% load can be equal to one hour operation at base load.