Belkacem Adouane

Gas turbine combustor for biomass derived LCV gas, a first approach towards fuel-NOx modelling and experimental validation

The section Thermal Power Engineering of Delft University of Technology operates a 1.5 MW pressurised fluidised bed gasification rig, including a hot gas cleaning unit and a pressurised downscaled Alstom gas turbines combustor. Regarding the combustion of low calorific value (LCV) gas, experiments are done to validate models describing turbulent steady state combustion. In this paper biomass derived LCV gas combustion experiments are described. The heating value of the gas was in the range of 2.5?4 MJ/mn3 and the process pressure was 3?8 bar. In all experiments, good combustion efficiency was observed. NOx formed, resulted from NH3 fueltextitnitrogen conversion to NOx was in the range of 10?60

Experimental Investigation on a Newly Designed Combustor for LCV Gas

Air blown gasification of biomass is one of the most promising and efficient ways to use alternative energy sources like organic matters from waste and biomass for producing LCV (Low Calorific Value) gas. This fuel is best used in highly efficient gas turbines (or combined cycles). The section Thermal Power Engineering of Delft University of Technology operates a 1.5 MW pressurized fluidized bed gasification rig, including a hot gas cleaning unit with the ability to test pressurized combustors designed and optimized for LCV gas combustion. In this paper, the results of six combustion experiments with the 1 MW non-swirling TUD (Technical University Delft) combustor are presented and compared with the results of experiments performed with a 1.0 MW swirling combustor designed by ALSTOM Power UK. The primary and cooling airflow of the TUD combustor can be altered independently for optimization purposes. The experiments were performed at 3.5 and 5.0 bara and stable combustion was accomplished with gas of heating values (HHV) ranging from 2.7 to 3.8 MJ/m3 n . Combustion efficiencies of the TUD combustor were well above 99.9% and emissions of CO were within the EU standards, except for one experiment where Minphyl as catalyst was added to the gasifier fuel. A high percentage of primary air was used in this experiment. Emissions of NO were outside the EU standards (100 ppm) for four of the six experiments because of the high fuel bound nitrogen (FBN) concentrations in the fuel gas. The FBN conversion rate ranged from 98% to 39% for FBN concentrations ranging from 238 to 2238 ppm.© 2003 ASME

Low Fuel-NOx Combustion of Synthetic LCV Gas

Fuel NOx is one of the main issues related to the combustion of biomass derived Low Calorific Value (LCV) Gas. The high NOx emissions accompanying the combustion of that fuel in gas turbines or gas engines are compromising the CO2 neutral character of biomass and are a barrier towards the introduction of this green energy source in the market. The reduction of NOx emissions has been one of the main preoccupations of researchers in the LCV gas combustion field. Although, much has been achieved for thermal NOx which is caused mainly by the conversion of the nitrogen of the air in high temperature regions, less work has been devoted to the reduction of fuel NOx , which has as a main source the fuel bound nitrogen FBN, namely ammonia in case of biomass. Reducing the conversion of the FBN to NOx has been the main issue in recent research work. However, fuel NOx could be reduced significantly applying methods; like washing the gas in a scrubber prior its entrance to the combustor, and SNCR or SCR methods applied at the exhaust. But those solutions stay very expensive in terms of polluted waste water and catalyst cost. In this paper, the approach is to reduce the conversion of FBN to NOx inside a newly designed combustor. The idea is to optimize the combustion process ending up with the lowest possible conversion of FBN to NOx . The LCV gas used in the experiments described in this paper is made by mixing CO, CO2 , H2 , natural gas and N2 with proportions comparable to those of the real LCV gas. This gas is then doped with NH3 to simulate the FBN. In this paper the conversion ratio of FBN to NOx versus the FBN concentration is presented. Furthermore, the system is investigated in terms of the effect of CH4 concentration on the conversion of FBN to NOx . And measurements along the combustor axis were performed with a traversing probe where temperature and important emissions along the axis were measured. In all the experiments described in the paper, The LCV gas has an HHV (High Calorific Value) ranging from 4 to 7Mj/nm3 . The newly designed combustor contains an embedded inner cylinder. In these experiments presented are without that embedded cylinder. The purpose of the current experiments is to be compared to the later experiments with the insert in order to define clearly the effect of the inner cylinder. Furthermore, this arrangement, i.e. without the insert, gave us the opportunity to traverse the combustor by a probe and to measure temperature and species profiles, which is of a great importance in defining the key parameter controlling the conversion of NH3 to NOx .Copyright

An Experimental Investigation of a Newly Designed Combustor for LCV Gas With Low NOx Emissions From Fuel Bound Nitrogen

Biomass derived LCV gas represents one of the best alternatives for fossil fuels. It is very attractive, because of its neutral aspects concerning CO2 emissions. However, on the other hand, the high content of fuel bound nitrogen results in high NOx emissions. This is one of the major problems related to the application of biomass derived LCV gas in gas turbines or gas engines. Reducing the conversion of fuel bound nitrogen (FBN) to NOx has been one of the main preoccupations for researchers working in the field of LCV gas combustion. At the section Energy Technology of Delft University of Technology, a group of researchers is busy with optimizing a newly designed combustor for LCV gas and low NOx emissions. With the new design, it is expected to end up with a very low conversion of FBN to NOx by optimizing the design and combustion process. The newly designed combustor is investigated experimentally and by CFD modeling. In this paper, the experimental part is presented. In all the experiments described below, natural gas diluted with nitrogen was the simulated LCV gas and ammonia (NH3 ) is injected into the fuel gas to simulate the FBN. The fuel gas has an HCV (High Calorific Value) of 5MJ/mn 3 . The combustor shows a very important optimal regime, where a minimum in conversion of FBN to NOx is achieved while maintaining a very low CO emissions. As low as 8% conversion ratio of NH3 to NOx has been achieved at high NH3 concentration in the LCV gas (3.45vol.%), and a minimum of 30% conversion was achieved for low ammonia concentrations (3100 ppmv).Copyright