Gas Turbine Combustion Technology Reducing Both Fuel-NOx and Thermal-NOx Emissions for Oxygen-Blown IGCC With Hot/Dry Synthetic Gas Cleanup

2006 ◽  
Vol 129 (2) ◽  
pp. 358-369 ◽  
Author(s):  
Takeharu Hasegawa ◽  
Takashi Tamaru
Keyword(s):  
Direct Injection ◽  
Combustion Method ◽  
Nox Emissions ◽  
Two Stage ◽  
Stage Combustion ◽  
Synthetic Gas ◽  
Combustion Technology ◽  
Thermal Nox ◽  
Combustion Tests ◽  
Fuel Nox

In order to improve the thermal efficiency of the oxygen-blown integrated gasification combined cycle (IGCC) and to meet stricter environmental restrictions among cost-effective options, a hot/dry synthetic gas cleanup is one of the most hopeful choices. The flame temperature of medium-Btu gasified fuel used in this system is high so that NOx formation by nitrogen fixation results to increase significantly. Additionally, the gasified fuel contains nitrogenous compound, as ammonia, and it produces nitrogen oxides, the fuel NOx, in the case of employing the hot/dry gas cleanup. Low NOx combustion technology to reduce both fuel-NOx and thermal-NOx emissions has been required to protect the environment and ensure low cost operations for all kinds of oxygen-blown IGCC. In this paper, we have demonstrated the effectiveness of two-stage combustion and nitrogen injection techniques, and also showed engineering guidelines for the low-NOx combustor design of oxygen-blown gasified, medium-Btu fuels. The main results obtained are as follows: (1) Based on the basic combustion tests using a small diffusion burner, we clarified that the equivalence ratio at the primary combustion zone has to be adjusted according to the fuel conditions, such as methane concentration, CO∕H2 molar ratio, and calorific values of gasified fuels in the case of the two-stage combustion method for reducing fuel-NOx emissions. (2) From the combustion tests of the medium-Btu fueled combustor, two-stage combustion with nitrogen direct injection into the combustor results in reductions of NOx emissions to 34ppm (corrected at 16% O2) or less under the gas turbine operational conditions of 25% load or higher for IGCC in the case where the gasified fuel contains 0.1% methane and 500ppm of ammonia. Through nitrogen direct injection, the thermal efficiency of the plant improved by approximately 0.3% (absolute), compared with the case where nitrogen was premixed with gasified fuel. The CO emission concentration decreased drastically, as low as 20ppm, or combustion efficiency was kept higher than 99.9%. The above results have shown that a two-stage combustion method with nitrogen direct injection is very effective for reducing both fuel-NOx and thermal-NOx emissions at once in IGCC, and it shows the bright prospects for low NOx and stable combustion technology of medium-Btu fuel.

Study of Medium-Btu Fueled Gas Turbine Combustion Technology for Reducing Both Fuel-NOx and Thermal-NOx Emissions in Oxygen-Blown IGCC

2002 ◽  
Author(s):  
Takeharu Hasegawa ◽  
Mikio Sato ◽  
Yasunari Katsuki ◽  
Tohru Hisamatsu
Keyword(s):  
Direct Injection ◽  
Combustion Method ◽  
Nox Emission ◽  
Two Stage ◽  
Gas Cleaning ◽  
Stage Combustion ◽  
Combustion Technology ◽  
Thermal Nox ◽  
Combustion Tests ◽  
Fuel Nox

In order to improve the thermal efficiency of the oxygen-blown IGCC (Integrated Gasification Combined Cycle) for stricter environmental standards and cost-effective option, it is necessary to adopt the hot/dry gas cleaning system. In this system, the flame temperature of medium-btu gasified fuel is higher and so NOx production from nitrogen fixation is expected to increase significantly. Also the gasified fuel contains fuel nitrogen, such as ammonia, in the case of employing the hot/dry gas cleaning system. This ammonia is easily oxidized into fuel-NOx in the combustor. For contribution to the protection of the environment and low cost operations of all kinds of oxygen-blown IGCC, low NOx combustion technology for reducing both the fuel-NOx and thermal-NOx emission has to be developed. In this paper, we clarified effectiveness of applying both the two-stage combustion and the nitrogen injection, and the useful engineering guidelines for the low-NOx combustor design of oxygen-blown gasified, medium-btu fuels. Main results obtained are as follows: (1) Based on the fundamental combustion tests using the small diffusion burner, we clarified that equivalence ratio at the primary combustion zone has to be adjusted due to the fuel conditions, such as methane concentration, CO/H2 molar ratio, and calorific values of gasified fuels in the case of the two-stage combustion method for reducing fuel-NOx emission. (2) From the combustion tests of the medium-btu fueled combustor the two-stage combustion with nitrogen direct injection into the combustor results in reduction of NOx emission to 80ppm (corrected at 16% O2) or less, the conversion rate of ammonia to NOx was 35% under the gas turbine operational conditions for IGCC in the case where fuel contains 3% of methane and 2135ppm of ammonia. By means of nitrogen direct injection, the thermal efficiency of the plant improved by approximately 0.3 percent (absolute), compared with a case where nitrogen is premixed with gasified fuel. The CO emission concentration decreased drastically, as low as 20ppm, or combustion efficiency was kept higher than 99.9%. Furthermore, based on the fundamental combustion tests’ results, the ammonia conversion rate is expected to decrease to 16% and NOx emission to 26ppm in the case of gasified fuel that contains 0.1% methane and 500ppm of ammonia. From the above results, it is clarified that two-stage combustion method with nitrogen injection is very effective for reducing both the fuel-NOx and thermal-NOx emissions at once in IGCC and it shows the bright prospects for low NOx and stable combustion technology of the medium-btu fuel.

An Experimental Study of Two-Stage Combustion Strategy on Combustion and Emission Characteristics in a Diesel Engine Fueled With Biodiesel Blends

2012 ◽  
Author(s):  
Donggon Lee ◽  
Kyusoo Jeong ◽  
Hyun Gu Roh ◽  
Chang Sik Lee
Keyword(s):  
Diesel Engine ◽  
Engine Speed ◽  
Direct Injection ◽  
Injection Timing ◽  
Emission Characteristics ◽  
Two Stage ◽  
Biodiesel Blends ◽  
Injection Quantity ◽  
Stage Combustion ◽  
Conventional Diesel Fuel

This study describes the effects of two-stage combustion (TSC) strategy on combustion and emission characteristics in 4 cylinder common-rail direct injection (CRDI) diesel engine fueled with biodiesel blends. In the present work, to investigate the combustion and emission characteristics, the experiments were performed under various injection pressures, first injection quantity and first injection timing of TSC strategy at constant engine speed and engine load. In addition, conventional diesel fuel (ULSD) was used to compare with biodiesel blends. The experimental results show that combustion of biodiesel blends is stable for various test conditions regardless of blending ratio, and indicated specific fuel consumption (ISFC) was increased as biodiesel blending ratio increased. In the emission characteristics, biodiesel blends generated lower indicated specific nitrogen oxides (IS-NOx) and indicated specific soot (IS-Soot) emissions compared to those of ULSD when the first injection quantity increased.

scholarly journals USE OF TWO-STAGE FUEL COMBUSTION TECHNOLOGY TO MINIMIZE HAZARDOUS EMISSIONS AT KAZAKHSTAN TPP

2021 ◽  
Vol 335 (1) ◽  
pp. 74-80
Author(s):  
A.S. Askarova ◽  
P. Safarik ◽  
S.A. Bolegenova ◽  
V.Yu. Maximov ◽  
A.O. Nugymanova ◽  
...  
Keyword(s):  
Combustion Chamber ◽  
Mass Transfer Process ◽  
Fuel Combustion ◽  
Low Grade ◽  
Two Stage ◽  
Entire Volume ◽  
Coal Fuel ◽  
Air Supply ◽  
Stage Combustion ◽  
Combustion Technology

Studies have been carried out using numerical modeling methods to determine the effect of the introduction of a two-stage combustion technology (OFA technology) of high-ash Karaganda coal on the characteristics of combustion processes: aerodynamics of flows, temperature and concentration (COх, NOх) fields throughout the entire volume of the combustion chamber of the BKZ-75 boiler at Shakhtinskaya TPP and at the outlet from it. Comparison with the basic regime of combustion of pulverized coal fuel, when there is no air supply through additional injectors (OFA = 0%). To implement the technology of two-stage combustion, various regimes of additional air supply through injectors were chosen: OFA equals 0% (basic version, conventional combustion), 5%, 10%, 15%, 18%, 20%, 25% and 30% of total air volume required for fuel combustion. A comparative analysis of the main characteristics of the heat and mass transfer process in the combustion chamber for the investigated modes is carried out. It is shown that an increase in the volume of additional air supplied through the injectors up to 18% leads to a decrease in the concentration of nitrogen oxide NO by 25% in comparison with traditional combustion. A further increase in the volume of additional air leads to a deterioration in these indicators. The results obtained will make it possible to optimize the combustion of low-grade fuel in the combustion chamber of the BKZ-75 boiler, increase the efficiency of fuel burnout, reduce harmful emissions and introduce a two-stage combustion technology at other coal-fired TPPs.

Combustion Technology in a Novel Gas Turbine System with Steam Injection and Two-Stage Combustion.

2001 ◽  
Vol 34 (9) ◽  
pp. 1159-1164 ◽  
Author(s):  
DAIQING ZHAO ◽  
YUKI OHNO ◽  
TOMOHIKO FURUHATA ◽  
HIROSHI YAMASHITA ◽  
NORIO ARAI ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Steam Injection ◽  
Two Stage ◽  
Stage Combustion ◽  
Combustion Technology

scholarly journals Study on a two-stage combustion method of woody biomass

2014 ◽  
Vol 80 (820) ◽  
pp. TEP0367-TEP0367 ◽  
Author(s):  
Fumiaki ABE ◽  
Masaya NAKAHARA ◽  
Kenichi TOKUNAGA
Keyword(s):  
Woody Biomass ◽  
Combustion Method ◽  
Two Stage ◽  
Stage Combustion

Low Fuel-NOx Combustion of Synthetic LCV Gas

2006 ◽  
Author(s):  
Belkacem Adouane ◽  
Guus Witteveen ◽  
Wiebren de Jong ◽  
Jos P. van Buijtenen
Keyword(s):  
Gas Turbines ◽  
Research Work ◽  
Combustion Process ◽  
Calorific Value ◽  
Green Energy ◽  
Nox Emissions ◽  
Gas Combustion ◽  
Reduction Of Nox ◽  
Thermal Nox ◽  
Fuel Nox

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.

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