Air Separation Membranes: An Alternative to EGR in Large Bore Natural Gas Engines

2010 ◽  
Vol 132 (8) ◽  
Author(s):  
Munidhar Biruduganti ◽  
Sreenath Gupta ◽  
Bipin Bihari ◽  
Steve McConnell ◽  
Raj Sekar
Keyword(s):  
Natural Gas ◽  
Equivalence Ratio ◽  
Nox Reduction ◽  
Engine Performance ◽  
Air Separation ◽  
Nox Emissions ◽  
Low Temperature Combustion ◽  
Lean Burn ◽  
Gas Combustion ◽  
Separation Membranes

Air separation membranes (ASMs) could potentially replace exhaust gas recirculation (EGR) technology in engines due to the proven benefits in NOx reduction but without the drawbacks of EGR. Previous investigations of nitrogen-enriched air (NEA) combustion using nitrogen bottles showed up to 70% NOx reduction with modest 2% nitrogen enrichment. The investigation in this paper was performed with an ASM capable of delivering at least 3.5% NEA to a single-cylinder spark-ignited natural gas engine. Low temperature combustion is one of the pathways to meet the mandatory ultra low NOx emissions levels set by regulatory agencies. In this study, a comparative assessment is made between natural gas combustion in standard air and 2% NEA. Enrichment beyond this level degraded engine performance in terms of power density, brake thermal efficiency (BTE), and unburned hydrocarbon emissions for a given equivalence ratio. The ignition timing was optimized to yield maximum brake torque for standard air and NEA. Subsequently, conventional spark ignition was replaced by laser ignition (LI) to extend lean ignition limit. Both ignition systems were studied under a wide operating range from ψ:1.0 to the lean misfire limit. It was observed that with 2% NEA, for a similar fuel quantity, the equivalence ratio (Ψ) increases by 0.1 relative to standard air conditions. Analysis showed that lean burn operation along with NEA and alternative ignition source, such as LI, could pave the pathway for realizing lower NOx emissions with a slight penalty in BTE.

NOx Emissions Reduction Using Air Separation Membranes for Different Loads in Gas-Fired Engines

2009 ◽  
Author(s):  
Munidhar Biruduganti ◽  
Sreenath Gupta ◽  
Bipin Bihari ◽  
Raj Sekar
Keyword(s):  
Natural Gas ◽  
Equivalence Ratio ◽  
Nox Reduction ◽  
Engine Performance ◽  
Air Separation ◽  
Nox Emissions ◽  
Low Temperature Combustion ◽  
Lean Burn ◽  
Gas Combustion ◽  
Separation Membranes

Air Separation Membranes (ASM) could potentially replace Exhaust Gas Recirculation (EGR) technology in engines due to the proven benefits in NOx reduction but without the drawbacks of EGR. Previous investigations of Nitrogen Enriched Air (NEA) combustion using nitrogen bottles showed up to 70% NOx reduction with modest 2% nitrogen enrichment. The investigation in this paper was performed with an ASM capable of delivering at least 3.5% NEA to a single cylinder spark ignited natural gas engine. Low Temperature Combustion (LTC) is one of the pathways to meet the mandatory ultra low NOx emissions levels set by regulatory agencies. In this study, a comparative assessment is made between natural gas combustion in standard air and 2% NEA for different engine loads. Enrichment beyond this level degraded engine performance in terms of power density, Brake Thermal Efficiency (BTE), and unburned hydrocarbon (UHC) emissions for a given equivalence ratio. The ignition timing was optimized to yield maximum brake torque for standard air and NEA. The parasitic loss associated with the usage of ASM technology is presented. It was observed that with 2% NEA, for a similar fuel quantity, the equivalence ratio (Ψ) increases by 0.1 relative to standard air conditions. Analysis showed that lean burn operation along with NEA could pave the pathway for realizing lower NOx emissions with a slight penalty in BTE.

Air Separation Membranes: An Alternative to EGR in Large Bore Natural Gas Engines

2009 ◽  
Author(s):  
Munidhar Biruduganti ◽  
Sreenath Gupta ◽  
Bipin Bihari ◽  
Steve McConnell ◽  
Raj Sekar
Keyword(s):  
Natural Gas ◽  
Equivalence Ratio ◽  
Nox Reduction ◽  
Engine Performance ◽  
Air Separation ◽  
Nox Emissions ◽  
Low Temperature Combustion ◽  
Lean Burn ◽  
Gas Combustion ◽  
Separation Membranes

Air Separation Membranes (ASM) could potentially replace Exhaust Gas Recirculation (EGR) technology in engines due to the proven benefits in NOx reduction but without the drawbacks of EGR. Previous investigations of Nitrogen Enriched Air (NEA) combustion using nitrogen bottles showed up to 70% NOx reduction with modest 2% nitrogen enrichment. The investigation in this paper was performed with an ASM capable of delivering at least 3.5% NEA to a single cylinder spark ignited natural gas engine. Low Temperature Combustion (LTC) is one of the pathways to meet the mandatory ultra low NOx emissions levels set by regulatory agencies. In this study, a comparative assessment is made between natural gas combustion in standard air and 2% NEA. Enrichment beyond this level degraded engine performance in terms of power density, Brake Thermal Efficiency (BTE), and unburned hydrocarbon (UHC) emissions for a given equivalence ratio. The ignition timing was optimized to yield maximum brake torque for standard air and NEA. Subsequently, conventional spark ignition (SI) was replaced by laser ignition (LI) to extend lean ignition limit. Both ignition systems were studied under a wide operating range from ψ: 1.0 to the lean misfire limit. It was observed that with 2% NEA, for a similar fuel quantity, the equivalence ratio (Ψ) increases by 0.1 relative to standard air conditions. Analysis showed that lean burn operation along with NEA and alternative ignition source such as LI could pave the pathway for realizing lower NOx emissions with a slight penalty in BTE.

Low Temperature Combustion Using Nitrogen Enrichment to Mitigate NOx From Large Bore Gas-Fueled Engines

2008 ◽  
Author(s):  
Munidhar S. Biruduganti ◽  
Sreenath B. Gupta ◽  
Raj Sekar
Keyword(s):  
Low Temperature ◽  
Power Density ◽  
Nox Reduction ◽  
Engine Performance ◽  
Air Separation ◽  
Nitrogen Enrichment ◽  
Nox Emissions ◽  
Low Temperature Combustion ◽  
Lean Burn ◽  
Temperature Combustion

Low Temperature Combustion (LTC) is identified as one of the pathways to meet the mandatory ultra low NOx emissions levels set by regulatory agencies. This phenomenon can be realized by utilizing various advanced combustion control strategies. The present work discusses nitrogen enrichment using an Air Separation Membrane (ASM) as a better alternative to the mature Exhaust Gas Re-circulation (EGR) technique currently in use. A 70% NOx reduction was realized with a moderate 2% nitrogen enrichment while maintaining power density and simultaneously improving Fuel Conversion Efficiency (FCE). The maximum acceptable Nitrogen Enriched Air (NEA) in a single cylinder spark ignited natural gas engine was investigated in this paper. Any enrichment beyond this level degraded engine performance both in terms of power density and FCE, and unburned hydrocarbon (UHC) emissions. The effect of ignition timing was also studied with and without N2 enrichment. Finally, lean burn versus stoichiometric operation utilizing NEA was compared. Analysis showed that lean burn operation along with NEA is one of the effective pathways for realizing better FCE and lower NOx emissions.

Low Temperature Combustion Using Nitrogen Enrichment to Mitigate NOx From Large Bore Natural Gas Fueled Engines

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
Munidhar S. Biruduganti ◽  
Sreenath B. Gupta ◽  
Raj Sekar
Keyword(s):  
Low Temperature ◽  
Natural Gas ◽  
Power Density ◽  
Nox Reduction ◽  
Air Separation ◽  
Nitrogen Enrichment ◽  
Nox Emissions ◽  
Low Temperature Combustion ◽  
Lean Burn ◽  
Temperature Combustion

Low temperature combustion is identified as one of the pathways to meet the mandatory ultra low NOx emissions levels set by the regulatory agencies. Exhaust gas recirculation (EGR) is a well known technique to realize low NOx emissions. However, EGR has many built-in adverse ramifications that negate its advantages in the long term. This paper discusses nitrogen enrichment of intake air using air separation membranes as a better alternative to the mature EGR technique. This investigation was undertaken to determine the maximum acceptable level of nitrogen enrichment of air for a single-cylinder spark-ignited natural gas engine. NOx reduction as high as 70% was realized with a modest 2% nitrogen enrichment while maintaining power density and simultaneously improving fuel conversion efficiency (FCE). Any enrichment beyond this level degraded engine performance in terms of power density, FCE, and unburned hydrocarbon emissions. The effect of ignition timing was also studied with and without N2 enrichment. Finally, lean burn versus stoichiometric operation utilizing nitrogen enrichment was compared. Analysis showed that lean burn operation along with nitrogen enrichment is one of the effective pathways for realizing better FCE and lower NOx emissions.

A Literature Review of NOx Formation Kinetics and a Prediction Method for Lean-Burn, Two-Stroke Natural Gas Engines

2019 ◽  
Author(s):  
Taylor F. Linker ◽  
Mark Patterson ◽  
Greg Beshouri ◽  
Abdullah U. Bajwa ◽  
Timothy J. Jacobs
Keyword(s):  
Natural Gas ◽  
Chemical Properties ◽  
Prediction Method ◽  
Operating Conditions ◽  
Combustion Mechanism ◽  
Nox Emissions ◽  
Lean Burn ◽  
Nox Formation ◽  
Gas Combustion ◽  
No2 Formation

Abstract The increased production of natural gas harvested from unconventional sources, such as shale, has led to fluctuations in the species composition of natural gas moving through pipelines. These variations alter the chemical properties of the bulk gas mixture and, consequently, affect the operation of pipeline compressor engines which use the gas as fuel. Among several possible ramifications of these variations is that of unacceptably high engine-out NOx emissions. Therefore, engine controller enhancements which can account for fuel variability are necessary for maintaining emissions compliance. Having the means to predict NOx emissions from a field engine can inform the development of such control schemes. There are several types of compressor engines; however, this study considers a large bore, lean-burn, two-stroke, integral compressor engine. This class of engine has unique operating conditions which make the formation of engine-out NOx different from typical automotive spark-ignited engines. For this reason, automotive-based methods for predicting NOx emissions are not sufficiently accurate. In this study, an investigation is performed on the possible NO and NO2 formation pathways which could be contributing to exhaust emissions. Additionally, a modeling method is proposed to predict engine-out NOx emissions using a 0-D/1-D model of a Cooper-Bessemer GMWH-10C compressor engine. Predictions are achieved with GRI-Mech3.0, a natural gas combustion mechanism, which allows for simulated formation of NOx species. The implemented technique is tuned using experimental data from a field engine to better predict emissions over a range of engine operating conditions. Tuning the model led to acceptable agreement across operating points varying in both load and trapped equivalence ratio.

Engine Capability Prediction for SI Engine Fueled With Syngas

2015 ◽  
Author(s):  
Hui Xu ◽  
Leon A. LaPointe
Keyword(s):  
Natural Gas ◽  
Solid Waste ◽  
Laminar Flame ◽  
Combustion Engine ◽  
Flame Temperature ◽  
Engine Performance ◽  
Nox Emissions ◽  
Lean Burn ◽  
Gaseous Fuels ◽  
Combustion Duration

There are increasing interests in converting solid waste or lignocellulosic biomass into gaseous fuels and using reciprocating internal combustion engine to generate electricity. A widely used technique is gasification. Gasification is a process where the solid fuel and air are introduced to a partial oxidation environment, and generate combustible gaseous called synthesis gas or syngas. Converting solid waste into gaseous fuel can reduce landfill and create income for process owners. However it can be very challenging to use syngas on a gaseous fueled spark ignited engine, such as a natural gas (NG) engine. NG engines are typically developed with pipeline quality natural gas (PQNG). NG engines can operate at lean burn spark ignited (LBSI), or stoichiometric with EGR spark ignited (SESI) conditions. This work discusses the LBSI engine condition. NG engines can perform very differently when fueled with nonstandard gaseous fuels such as syngas without appropriate tuning. It is necessary to evaluate engine performance in terms of combustion duration, relative knock propensity and NOx emissions for such applications. Due to constraints in time and resources it is often not feasible to test such fuel blends in the laboratory. An analytical method is needed to predict engine performance in a timely manner. This study investigated the possibility of using syngas on a spark ignited engine developed with PQNG. Engine performance was predicted using in house developed models and PQNG as the reference fuel. Laminar flame speed (LFS), adiabatic flame temperature (AFT) and Autoignition interval (AI) are used to predict combustion duration, engine out NOx and engine knock propensity relative to NG at the target Lambda values. Single cylinder research engine data obtained under lean burn conditions fueled with PQNG was selected as the baseline. LFS, AFT and AI of syngas were computed at reference conditions. Lambda of operation was predicted for syngas to provide the same burn rate as NG at the reference Lambda value for NG. Analysis shows that, using syngas at the selected Lambda, the engine can have less engine out NOx emissions and less knock propensity relative to NG at the same speed and load. Modifications to fuel system components may be required to avoid engine derate.

Performance of a Natural Gas Engine Using Variable Air Composition

2005 ◽  
Author(s):  
Munidhar S. Biruduganti ◽  
Sreenath B. Gupta ◽  
Steve McConnell ◽  
Raj Sekar
Keyword(s):  
Natural Gas ◽  
Nox Reduction ◽  
Air Separation ◽  
The Other ◽  
Polymeric Membrane ◽  
Nitrogen Enrichment ◽  
Nox Emissions ◽  
Ignition Timing ◽  
Other Hand ◽  
Separation Membrane

A comparative analysis of nitrogen and oxygen enriched combustion is presented in this paper. Nitrogen enrichment of intake air is proposed as an alternative to Exhaust Gas Recirculation (EGR). NOx reduction by EGR is not very promising due to engine reliability concerns and increased maintenance costs. Air separation membrane, on the other hand, is a potential strategy for NOx reduction due to uncompromised reliability of engine performance. Oxygen-rich and nitrogen-rich streams are produced by passing air through a nonporous polymeric membrane. Nitrogen Enriched Air (NEA) reduces NOx formation by lowering in-cylinder combustion temperatures but with a compromise in Fuel Conversion Efficiency (FCE). However, advanced ignition timing improves FCE considerably. Oxygen Enriched Air (OEA), on the other hand, improves FCE due to the availability of extra oxygen for better combustion which results in higher bulk gas temperatures and NOx emissions. This behavior could be controlled by retarding the ignition timing. Experimental results of nitrogen and oxygen enriched combustion of a Kohler M12 generator (converted to operate with natural gas) is presented in this paper. A 68% reduction in NOx and a 0.8% drop in FCE were observed at −30 ATDC ignition timing (IT) with 2.1% N2 enrichment (40 slpm). A 9% O2 enrichment (40 slpm) at −30 ATDC IT improved FCE by 1% but with higher NOx emissions. The increase in NOx emissions was minimal with a 2% improvement in FCE at −10 ATDC IT and 9% O2 enrichment (40 slpm). Some of the drawbacks encountered were engine misfire at higher concentrations of nitrogen enriched air and retarded ignition timing resulting in poor FCE. This paper discusses both the approaches and highlights the benefits of nitrogen enrichment using an air separation membrane over its counterpart for NOx reduction.

Strategies for Reduced NOx Emissions in Pilot-Ignited Natural Gas Engines

2002 ◽  
Author(s):  
Sundar R. Krishnan ◽  
Kalyan K. Srinivasan ◽  
Weidong Gong ◽  
Scott Fiveland ◽  
Satbir Singh ◽  
...  
Keyword(s):  
Natural Gas ◽  
Fuel Injection ◽  
Nox Reduction ◽  
Engine Performance ◽  
Injection Timing ◽  
Nox Emissions ◽  
Pilot Injection ◽  
Engine Operation ◽  
Performance And Emissions ◽  
Inlet Conditions

The performance and emissions of a single-cylinder, natural gas fueled engine using a pilot ignition strategy have been investigated. Small diesel pilots (2–3 percent on an energy basis), when used to ignite homogeneous natural gas-air mixtures, are shown to possess the potential for reduced NOx emissions while maintaining good engine performance. The effect of pilot injection timing, intake charge pressure, and charge temperature on engine performance and emissions with natural gas fueling was studied. With appropriate control of the above variables, engine-out brake specific NOx emissions could be reduced to the range of 0.07–0.10 g/kWh from the baseline diesel (with mechanical fuel injection) value of 10.5 g/kWh. For this NOx reduction, the decrease in fuel conversion efficiency from the baseline diesel value was approximately 1–2 percent. Total unburned hydrocarbon (HC) emissions and carbon monoxide (CO) emissions were higher with natural gas operation. Heat release schedules obtained from measured cylinder pressure data are also presented. The importance of pilot injection timing and inlet conditions on the stability of engine operation and knock are also discussed.

Strategies for Reduced NOx Emissions in Pilot-Ignited Natural Gas Engines

2003 ◽  
Vol 126 (3) ◽  
pp. 665-671 ◽  
Author(s):  
S. R. Krishnan ◽  
K. K. Srinivasan ◽  
S. Singh ◽  
S. R. Bell ◽  
K. C. Midkiff ◽  
...  
Keyword(s):  
Natural Gas ◽  
Fuel Injection ◽  
Nox Reduction ◽  
Engine Performance ◽  
Injection Timing ◽  
Nox Emissions ◽  
Pilot Injection ◽  
Engine Operation ◽  
Performance And Emissions ◽  
Inlet Conditions

The performance and emissions of a single-cylinder natural gas fueled engine using a pilot ignition strategy have been investigated. Small diesel pilots (2–3% on an energy basis), when used to ignite homogeneous natural gas-air mixtures, are shown to possess the potential for reduced NOx emissions while maintaining good engine performance. The effects of pilot injection timing, intake charge pressure, and charge temperature on engine performance and emissions with natural gas fueling were studied. With appropriate control of the above variables, it was shown that full-load engine-out brake specific NOx emissions could be reduced to the range of 0.07–0.10 g/kWh from the baseline diesel (with mechanical fuel injection) value of 10.5 g/kWh. For this NOx reduction, the decrease in fuel conversion efficiency from the baseline diesel value was approximately one to two percentage points. Total unburned hydrocarbon (HC) emissions and carbon monoxide (CO) emissions were higher with natural gas operation. The nature of combustion under these conditions was analyzed using heat release schedules predicted from measured cylinder pressure data. The importance of pilot injection timing and inlet conditions on the stability of engine operation and knock are also discussed.

Engine Capability Prediction for Spark Ignited Engine Fueled With Syngas

2016 ◽  
Vol 138 (10) ◽  
Author(s):  
Hui Xu ◽  
Leon A. LaPointe
Keyword(s):  
Natural Gas ◽  
Solid Waste ◽  
Combustion Engine ◽  
Flame Temperature ◽  
Engine Performance ◽  
Nox Emissions ◽  
Si Engine ◽  
Lean Burn ◽  
Gaseous Fuels ◽  
Combustion Duration

Abstract There are increasing interests in converting solid waste or lignocellulosic biomass into gaseous fuels and using reciprocating internal combustion engine to generate electricity. A widely used technique is gasification. Gasification is a process where the solid fuel and air are introduced to a partial oxidation environment, and generate combustible gaseous called synthesis gas or syngas. Converting solid waste into gaseous fuel can reduce landfill and create income for process owners. However, it can be very challenging to use syngas on a gaseous fueled spark ignited (SI) engine, such as a natural gas (NG) engine. NG engines are typically developed with pipeline quality natural gas (PQNG). NG engines can operate at lean burn spark ignited (LBSI), or stoichiometric with exhaust gas recirculation (EGR) spark ignited (SESI) conditions. This work discusses the LBSI engine condition. NG engines can perform very differently when fueled with nonstandard gaseous fuels such as syngas without appropriate tuning. It is necessary to evaluate engine performance in terms of combustion duration, relative knock propensity, and NOx emissions for such applications. Due to constraints in time and resources it is often not feasible to test such fuel blends in the laboratory. An analytical method is needed to predict engine performance in a timely manner. This study investigated the possibility of using syngas on an SI engine developed with PQNG. Engine performance was predicted using in house developed models and PQNG as the reference fuel. Laminar flame speed (LFS), adiabatic flame temperature (AFT), and auto-ignition interval (AI) are used to predict combustion duration, engine out NOx and engine knock propensity relative to NG at the target lambda values. Single cylinder research engine data obtained under lean burn conditions fueled with PQNG was selected as the baseline. LFS, AFT, and AI of syngas were computed at reference conditions. Lambda of operation was predicted for syngas to provide the same burn rate as NG at the reference lambda value for NG. Analysis shows that, using syngas at the selected lambda, the engine can have less engine out NOx emissions and less knock propensity relative to NG at the same speed and load. Modifications to fuel system components may be required to avoid engine derate.

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