Papers by Author: Yu Qi Jin

Abstract: Thermogravimetric analysis (TGA), coupled with Fourier transform infrared analysis (TG-FTIR) of sewage sludge was carried out to investigate the influence of moisture and oxygen on gas evolution during pyrolysis of sewage sludge. Wet sewage sludge with moisture of 86.47(wt. %) was collected from Shanghai, China. Wet sewage sludge and air dried sewage sludge were used in TG-FTIR analysis, while combustion (air flow) and pyrolysis (nitrogen flow) were separately introduced to achieve comparison. In condition of dry sewage sludge pyrolysis, there were two peaks representing release of separately moisture and volatile. Weight lost 85% in the temperature range of 25-600 °C while the main volatile matters were released before 600 °C. When air flow was introduced, a third peak of char combustion occurred. Wet sewage sludge made no much difference, except for the relatively outstanding peak of moisture release. Temperature regions for each stage were the same for wet and dry sewage sludge from TG curve. However, from the FTIR analysis, ammonia has two peaks between 50 and 450 °C in pyrolysis while ammonia has only one peak between 50 and 300°C.

Abstract: Oily sludge is inevitably produced in numerous petroleum processing operations. Five oily sludge samples were collected to identify the compositions and to characterize the extracted solids. The results indicated that three fifths of the samples contained significant amounts of oil and could be potentially recovered as energy resources. All of the samples had high concentration of water. The compositions of C, H, and N, as well as H/C in the separated oils were close to those in oil sands bitumen. The high concentration of asphaltenes agreed with the low H/C. The XRD spectra showed that the major minerals contained in the extracted solids were quartz and calcite.

Abstract: In this paper, the classical sewage sludge and coal co-combustion power generating system was optimized. The regenerative steam in the extraction turbine was partly used for the sludge drying. And then, the mathematics model was established based on the exergy theory. Several extraction points were compared to find out the most optimization parameters (drying efficiency of the dryer, pressure and tempreture). The result showed that, with different steam temperature and pressure at different extraction points, the influence to the system exergy efficiency caused by the percentage of moisture and drying efficiency was different. When the sludge moisture content went to about 35%, the generating capacity increment was moderating. After the calculation and comparison, the error between the calculation results of the mathematical optimization model and the classical thermodynamic method was very small. The calculation in mathematical optimization model based on exergy analysis was relatively simple, and analysis of the relationship between variables was easier.