Modelling Trace Element Emissions in Co-Gasification of Sewage Sludge With Coal

2002 ◽  
Author(s):  
G. P. Reed ◽  
D. R. Dugwell ◽  
R. Kandiyoti
Keyword(s):  
Experimental Data ◽  
Trace Elements ◽  
Sewage Sludge ◽  
Trace Element ◽  
Energy Recovery ◽  
Pilot Scale ◽  
Gaseous Species ◽  
Fuel Gas ◽  
Gas Cleaning ◽  
Hot Gas

Gasification has attracted considerable interest from water utilities as a sewage sludge disposal option, with the advantages of waste volume reduction, pathogen destruction and energy recovery. Co-gasification with coal in a larger plant (>10 MWt) employing a gas turbine for energy recovery may reduce the risk and cost of this option. However, controlling the release of trace elements such as Pb and Zn in the gas produced may be necessary to avoid corrosion, and to meet environmental requirements. A thermodynamic equilibrium model has been used to make predictions of the speciation of trace elements in the fuel gas from co-gasification of sewage sludge with coal. Experimental data from a pilot scale 2 MWt sewage sludge/coal co-gasification plant with a hot gas filter was used to test the validity of these predictions. No significant amount of Be, Co, Cu, V and Zn was predicted to be in the form of gaseous phase species, and this was confirmed by the experimental data. On the other hand, Hg and Se were predicted to be only present in gas phase species, and this was also confirmed experimentally. The elements As, B, Cd, Pb, Sb and Sn were all predicted to form a larger amount of gaseous species than was observed in the experimental measurements. Refinement of the predictions for As and B by inclusion of specific minor/trace element interactions with Ni and Ca respectively gave a better agreement with the experimental data. Whilst the experimentally-observed lowering of Pb emissions by reduction of the gas cleaning temperature from 580 °C to 450 °C was qualitatively predicted, the concentration of Pb in the fine dust removed by the hot gas filter indicates condensation at higher temperatures than predicted. The absence of thermodynamic data for the more complex minerals and adsorbed species that may be formed is thought to account for some of these differences.

scholarly journals Technical Evaluation of Simplified IGCC Components

1985 ◽  
Author(s):  
M. W. Horner ◽  
R. K. Alff ◽  
J. C. Corman
Keyword(s):  
Gas Turbine ◽  
Power Plants ◽  
Fixed Bed ◽  
Exhaust System ◽  
Pilot Scale ◽  
Combined Cycle ◽  
Fuel Gas ◽  
Capital Costs ◽  
Coal Gas ◽  
Hot Gas

Simplified integrated gasification combined cycle (IGCC) power plants offer attractive advantages for improving the performance of coal to electricity systems. This plant configuration, which utilizes a coal gasifier, hot gas cleanup system, and gas turbine combined cycle, has the potential to reduce both capital costs for equipment and fuel costs through improved efficiency. This paper reports the results of fuel supply and gas turbine testing on actual hot low-Btu coal gas. A pilot-scale advanced fixed-bed gasifier has been modified to supply hot coal gas to a particulate removal cyclone and then to a gas turbine simulator. The hot gas is combusted in a General Electric MS6000 combustor developed for low-Btu gas fuel. The combusted product flows through a MS6000 turbine first-stage nozzle sector. The exhaust gases from the nozzle sector pass over air-cooled cylindrical ash deposition pin specimens and then into a water quench exhaust system. Extensive instrumentation and sampling provisions are utilized to characterize the fuel gas, the combustion gases, and the ash deposits formed on turbine components. Two regimes of nozzle metal surface temperatures have been investigated by separate testing performed including 500–600 °F with water-cooled and 1500–1650 °F with air-cooled nozzle sectors. Results from the test program have provided key data related to fuel gas cleanup and the tolerance of gas turbine hot gas path parts to the products of combustion from coal-derived fuels.

High-temperature fuel gas cleaning and removal of alkalis using molten slag

1998 ◽  
Vol 212 (3) ◽  
pp. 151-158 ◽  
Author(s):  
H W Gudenau ◽  
H Hoberg ◽  
A R Pande ◽  
M Weinberg ◽  
J-E Becker
Keyword(s):  
High Temperature ◽  
Molten Slag ◽  
Combined Cycle ◽  
Simultaneous Removal ◽  
Fuel Gas ◽  
Gas Cleaning ◽  
Hot Gas ◽  
Particulate Removal ◽  
Hot Gas Cleaning ◽  
Major Emphasis

Fuel gas cleaning is an important step in the development of coal-based combined cycle technologies. By integrating hot gas cleaning facilities in the combined cycle power plant, higher operating temperatures can be achieved. Research is being carried out at the Institute of Ferrous Metallurgy, Technical University of Aachen, to develop a process for gas cleaning at temperatures above 1300°C using a venturi scrubber with molten slags as sorbents. This process offers simultaneous removal of particulate matter and alkali vapours in the gas stream. The present paper deals with the particulate removal tests, with major emphasis on investigations carried out to study the reaction between molten slags of various compositions and alkali vapours. These investigations included thermochemical calculations as well as an experimental reaction study.

Gasification Tests With Sewage Sludge and Coal/Sewage Sludge Mixtures in a Pilot Scale, Air Blown, Spouted Bed Gasifier

2002 ◽  
Author(s):  
N. Paterson ◽  
G. P. Reed ◽  
D. R. Dugwell ◽  
R. Kandiyoti
Keyword(s):  
Sewage Sludge ◽  
Pilot Scale ◽  
Process Performance ◽  
Spouted Bed ◽  
Fuel Conversion ◽  
Fuel Gas ◽  
Bed Height ◽  
Coal Mixtures ◽  
Very High

A series of tests have been done in a pilot scale air blown gasifier, to assess the performance of sewage sludge pellets and sewage sludge pellet/coal mixtures. The aim has been to compare the performances with that achieved with coal alone and to assess the suitability of the sewage containing fuel as a candidate fuel for the Air Blown Gasification Cycle (ABGC). The co-gasification of sewage sludge with coal raised both the CV of the fuel gas and the fuel conversion compared with values achieved with coal alone. The mixtures were operated under very similar conditions to those needed with coal and no adverse operational problems were encountered. A lower fluidising velocity was needed with the neat pellets to enable a stable bed height to be achieved. However, the conversion of the pellets to gas was very high and the fuel gas CV was higher than that achieved during the co-gasification tests. Overall, the results suggest that sewage based materials are suitable for use in the ABGC and that their use can improve the process performance.

Catalytic Hot Gas Cleaning of Fuel Gas from an Air-Blown Pressurized Fluidized-Bed Gasifier

2000 ◽  
Vol 39 (11) ◽  
pp. 4075-4081 ◽  
Author(s):  
Wuyin Wang ◽  
Nader Padban ◽  
Zhicheng Ye ◽  
Göran Olofsson ◽  
Arne Andersson ◽  
...  
Keyword(s):  
Fluidized Bed ◽  
Fuel Gas ◽  
Gas Cleaning ◽  
Hot Gas ◽  
Fluidized Bed Gasifier ◽  
Hot Gas Cleaning

scholarly journals Enhancement of Methanogenic Activity in Volumetrically Undersized Reactor by Mesophilic Co-Digestion of Sewage Sludge and Aqueous Residue

2021 ◽  
Vol 13 (14) ◽  
pp. 7728
Author(s):  
Vincenzo Torretta ◽  
Athanasia K. Tolkou ◽  
Ioannis A. Katsoyiannis ◽  
Francesca Maria Caccamo ◽  
Marco Carnevale Miino ◽  
...  
Keyword(s):  
Sewage Sludge ◽  
Energy Recovery ◽  
Hydraulic Retention Time ◽  
Biogas Production ◽  
Treatment Plant ◽  
Pilot Scale ◽  
Methanogenic Activity ◽  
Anaerobic Reactors ◽  
Aqueous Residue ◽  
First Time

To date, energy recovery from biological sewage sludge (BSS) by anaerobic digestion has been very popular. However, it can often happen that anaerobic reactors are volumetrically undersized, thus reducing performance in terms of biogas production. A continuous-flow pilot-scale plant was used to investigate, for the first time, the effects of mesophilic anaerobic co-digestion (MACoD) of sewage sludge and aqueous residue (AR) from a biosolids treatment plant (BTP) on methanogenic activity under low hydraulic retention time (HRT) conditions (to simulate the undersizing of the reactor). The results showed that the digestate is always more rapidly biodegradable than the matrices fed, while particulate COD hydrolyzed (12 ± 1.3%) is independent of the quantity of AR dosed. Feeding over 35% of soluble OLR, the total VFAs in the system strongly decreased, despite the low HRT. In correspondence with higher dosages of AR, the percentage of CH4 increased up to 77–78% and the CO2 CH4−1 ratio decreased to 0.25 ± 0.2. Specific methane production increased from 0.09 ± 0.01 m3CH4 kgCODremoved−1 with BSS alone to 0.28 ± 0.01 m3CH4CH4 kgCODremoved−1 in the case of BSS co-digested with AR. Moreover, co-digestion with AR from a BTP allowed continuous specific methanogenic activity to be enhanced from 1.76 ± 0.02 m3CH4 tVSS−1 d−1 to 6.48 ± 0.88 m3CH4 tVSS−1 d−1. Therefore, the MACoD of BSS and AR from a BTP could be a good solution to enhance methanogenic activity in a volumetrically undersized anaerobic digester with reduced HRT.

Gasification as an optimum alternative for the sludge management

2011 ◽  
Vol 6 (4) ◽  
Author(s):  
C. Peregrina ◽  
J. M. Audic ◽  
P. Dauthuille
Keyword(s):  
Power Generation ◽  
Anaerobic Digestion ◽  
Sewage Sludge ◽  
Combined Heat And Power ◽  
Gas Production ◽  
Waste Reduction ◽  
Fluidised Bed ◽  
Sludge Management ◽  
Gas Cleaning ◽  
Cleaning System

Assimilate sludge to a fuel is not new. Sludge incineration and Combined Heat and Power (CHP) engines powered with sludge-derived anaerobic digestion gas (ADG) are operations widely used. However, they have a room of improvement to reach simultaneously a positive net power generation and a significant level of waste reduction and stabilization. Gasification has been used in other realms for the conversion of any negative-value carbon-based materials, that would otherwise be disposed as waste, to a gaseous product with a usable heating value for power generation . In fact, the produced gas, the so-called synthetic gas (or syngas), could be suitable for combined heat and power motors. Within this framework gasification could be seen as an optimum alternative for the sludge management that would allow the highest waste reduction yield (similar to incineration) with a high power generation. Although gasification remains a promising route for sewage sludge valorisation, campaigns of measurements show that is not a simple operation and there are still several technical issues to resolve before that gasification was considered to be fully applied in the sludge management. Fluidised bed was chosen by certain technology developers because it is an easy and well known process for solid combustion, and very suitable for non-conventional fuels. However, our tests showed a poor reliable process for gasification of sludge giving a low quality gas production with a significant amount of tars to be treated. The cleaning system that was proposed shows a very limited removal performance and difficulties to be operated. Within the sizes of more common WWTP, an alternative solution to the fluidised bed reactor would be the downdraft bed gasifier that was also audited. Most relevant data of this audit suggest that the technology is more adapted to the idea of sludge gasification presented in the beginning of this paper where a maximum waste reduction is achieved with a great electricity generation thanks to the use of a “good” quality syngas in a CHP engine. Audit show also that there is still some work to do in order to push sludge gasification to a more industrial stage. Regardless what solution would be preferred, the resulting gasification system would involve a more complex scenario compared to Anaerobic Digestion and Incineration, characterised by a thermal dryer and gasifier with a complete gas cleaning system. At the end, economics, reliability and mass and energy yields should be carefully analysed in order to set the place that gasification would play in the forthcoming processing of sewage sludge.

Methylmercury and Trace Element Distribution in the Organs of Stenella coeruleoalba Dolphins Stranded on the French Mediterranean Coast

2014 ◽  
Vol 8 (1) ◽  
pp. 35-48 ◽  
Author(s):  
Emmanuel Wafo ◽  
Véronique Risoul ◽  
Thérèse Schembri ◽  
Véronique Lagadec ◽  
Frank Dhermain ◽  
...  
Keyword(s):  
Trace Elements ◽  
Trace Element ◽  
Marine Pollution ◽  
Element Distribution ◽  
Mediterranean Coast ◽  
Trace Element Distribution ◽  
Slight Reduction ◽  
Stenella Coeruleoalba ◽  
Contamination Levels

The main objective of this study was to evaluate the contamination by mercury (Hg), methylmercury (Me-Hg), cadmium (Cd), selenium (Se), zinc (Zn), copper (Cu), iron (Fe) and manganese (Mn) in dolphins stranded on the French Mediterranean coast. The distributions of these contaminants in the organs of dolphins have also been studied. Overall, contamination levels varied according to the following sequence: liver > kidney > lung > muscle, except for cadmium (kidney > liver > lung > muscle). Size and sex of animals were also considered. Young dolphins were less impacted with trace elements than adults, except for copper. Among the studied parameters, the most important appeared to be the size of mammals. In addition, in the case of mercury and selenium, the sex of mammals seemed to be also relevant. The correlations between the concentrations of trace elements suggest the existence of detoxification processes. Since 1990s, using dolphins for tracing marine pollution, a slight reduction in the burden of the considered trace elements could be noted.

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