Performance of a Large Bore Natural Gas Engine With Reformed Natural Gas Prechamber Fueling

2010 ◽  
Author(s):  
Matthew D. Ruter ◽  
Daniel B. Olsen ◽  
Mark V. Scotto ◽  
Mark A. Perna
Keyword(s):  
Carbon Monoxide ◽  
Natural Gas ◽  
Equivalence Ratio ◽  
High Energy ◽  
Gaseous Fuel ◽  
Combustion Stability ◽  
Injection Timing ◽  
Nox Emissions ◽  
Combustion Instabilities ◽  
Operating Points

Lean combustion is a standard approach used to reduce NOx emissions in large bore natural gas engines. However, at lean operating points, combustion instabilities and misfires give rise to high total hydrocarbon (THC) and carbon monoxide (CO) emissions. To counteract this effect, precombustion chamber (PCC) technology is employed to allow engine operation at an overall lean equivalence ratio while mitigating the rise of THC and CO caused by combustion instability and misfires. A PCC is a small chamber, typically 1–2% of the clearance volume. A separate fuel line supplies gaseous fuel to the PCC and a standard spark plug ignites the slightly rich mixture (equivalence ratio 1.1 to 1.2) in the PCC. The ignited PCC mixture enters the main combustion chamber as a high energy flame jet, igniting the lean mixture in the main chamber. Typically, natural gas fuels both the main cylinder and the PCC. In the current research, a mixture of reformed natural gas (syngas) and natural gas fuels the PCC. Syngas is a broad term that refers to a synthetic gaseous fuel. In this case, syngas specifically denotes a mixture of hydrogen, carbon monoxide, nitrogen, and methane generated in a natural gas reformer. Syngas has a faster flame speed and a wider equivalence ratio range of operation. Fueling the PCC with Syngas reduces combustion instabilities and misfires. This extends the overall engine lean limit, enabling further NOx reductions. Research results presented are aimed at quantifying the benefits of syngas PCC fueling. A model is developed to predict equivalence ratio in the PCC for different mixtures and flowrates of fuel. An electronic injection valve is used to supply the PCC with syngas. The delivery pressure, injection timing, and flow rate are varied to optimize PCC equivalence ratio. The experimental results show that supplying the PCC with syngas improves combustion stability by 16% compared to natural gas PCC fueling. Comparing equivalent combustion stability operating points between syngas mixtures and natural gas shows a 40% reduction in NOx emissions when fueling the PCC with syngas mixtures compared to natural gas fueling.

scholarly journals Comparison of performance of biodiesels of mahua oil and gingili oil in dual fuel engine

2008 ◽  
Vol 12 (1) ◽  
pp. 151-156 ◽  
Author(s):  
Kapilan Nadar ◽  
Pratap Reddy ◽  
Rao Anjuri
Keyword(s):  
Carbon Monoxide ◽  
Methyl Ester ◽  
Dual Fuel ◽  
Injection Timing ◽  
Nox Emissions ◽  
Test Results ◽  
Liquefied Petroleum Gas ◽  
Mahua Oil ◽  
Hydro Carbon ◽  
Pilot Fuel

In this work, an experimental work was carried out to compare the performance of biodiesels made from non edible mahua oil and edible gingili oil in dual fuel engine. A single cylinder diesel engine was modified to work in dual fuel mode and liquefied petroleum gas was used as primary fuel. Biodiesel was prepared by transesterification process and mahua oil methyl ester (MOME) and gingili oil methyl ester (GOME) were used as pilot fuels. The viscosity of MOME is slightly higher than GOME. The dual fuel engine runs smoothly with MOME and GOME. The test results show that the performance of the MOME is close to GOME, at the pilot fuel quantity of 0.45 kg/h and at the advanced injection timing of 30 deg bTDC. Also it is observed that the smoke, carbon monoxide and unburnt hydro carbon emissions of GOME lower than the MOME. But the GOME results in slightly higher NOx emissions. From the experimental results it is concluded that the biodiesel made from mahua oil can be used as a substitute for diesel in dual fuel engine.

Hydrogen enrichment: A way to maintain combustion stability in a natural gas fuelled engine with exhaust gas recirculation, the potential of fuel reforming

2001 ◽  
Vol 215 (3) ◽  
pp. 405-418 ◽  
Author(s):  
S. Allenby ◽  
W-C. Chang ◽  
A. Megaritis ◽  
M. L. Wyszyński
Keyword(s):  
Natural Gas ◽  
Exhaust Gas Recirculation ◽  
Combustion Stability ◽  
Exhaust Gas ◽  
Fuel Reforming ◽  
Rapid Reduction ◽  
Indicated Mean Effective Pressure ◽  
Hydrogen Enrichment ◽  
Gas Recirculation ◽  
Operating Points

An experimental study was carried out to evaluate the potential of hydrogen enrichment to increase the tolerance of a stoichiometrically fuelled natural gas engine to high levels of dilution by exhaust gas recirculation (EGR). This provides significant gains in terms of exhaust emissions without the rapid reduction in combustion stability typically seen when applying EGR to a methane-fuelled engine. Presented results give the envelope of benefits from hydrogen enrichment. In parallel, the performance of a catalytic exhaust gas reforming reactor was investigated in order that it could be used as an onboard source of hydrogen-rich EGR. It was shown that sufficient hydrogen was generated with currently available prototype catalysts to allow the engine, at the operating points considered, to tolerate up to 25 per cent EGR, while maintaining a coefficient of variability of indicated mean effective pressure below 5 per cent. This level of EGR gives a reduction in NO emissions greater than 80 per cent in all test cases.

Impact of Cooling Air Injection on the Combustion Stability of a Premixed Swirl Burner Near Lean Blowout

2013 ◽  
Vol 135 (11) ◽  
Author(s):  
A. Marosky ◽  
V. Seidel ◽  
T. Sattelmayer ◽  
F. Magni ◽  
W. Geng
Keyword(s):  
Flame Front ◽  
Equivalence Ratio ◽  
Flame Stabilization ◽  
Air Injection ◽  
Combustion Stability ◽  
Nox Emissions ◽  
Test Rig ◽  
Lean Blowout ◽  
Burner Exit ◽  
Cooling Air

In most dry, low-NOx combustor designs of stationary gas turbines, the front panel impingement cooling air is directly injected into the combustor primary zone. This air partially mixes with the swirling flow of premixed reactants from the burner and reduces the effective equivalence ratio in the flame. However, local unmixedness and the lean equivalence ratio are supposed to have a major impact on combustion performance. The overall goal of this investigation is to answer the question of whether the cooling air injection into the primary combustor zone has a beneficial effect on combustion stability and NOx emissions or not. The flame stabilization of a typical swirl burner with and without front panel cooling air injection is studied in detail under atmospheric conditions close to the lean blowout limit (LBO) in a full-scale, single-burner combustion test rig. Based on previous isothermal investigations, a typical injection configuration is implemented for the combustion tests. Isothermal results of experimental studies in a water test rig adopting high-speed planar laser-induced fluorescence (HSPLIF) reveal the spatial and temporal mixing characteristics for the experimental setup studied under atmospheric combustion. This paper focuses on the effects of cooling air injection on both flame dynamics and emissions in the reacting case. To reveal dependencies of cooling air injection on combustion stability and NOx emissions, the amount of injected cooling air is varied. OH*-chemiluminescence measurements are applied to characterize the impact of cooling air injection on the flame front. Emissions are collected for different cooling air concentrations, both global measurements at the chamber exit, and local measurements in the region of the flame front close to the burner exit. The effect of cooling air injection on pulsation level is investigated by evaluating the dynamic pressure in the combustor. The flame stabilization at the burner exit changes with an increasing degree of dilution with cooling air. Depending on the amount of cooling, only a specific share of the additional air participates in the combustion process.

Development of Advanced Laser Ignition System for Stationary Natural Gas Reciprocating Engines

2005 ◽  
Author(s):  
Bipin Bihari ◽  
Sreenath B. Gupta ◽  
Raj R. Sekar ◽  
Jess Gingrich ◽  
Jack Smith
Keyword(s):  
Natural Gas ◽  
Operating Conditions ◽  
Combustion Stability ◽  
Laser Ignition ◽  
Nox Emissions ◽  
Ignition System ◽  
Performance Improvements ◽  
Discharge Ignition ◽  
Reciprocating Engines ◽  
Load Conditions

Laser ignition is considered the prime alternative to conventional coil based ignition for improving efficiency and simultaneously reducing NOx emissions in lean-burn natural gas fired stationary reciprocating engines. In this paper, Argonne’s efforts towards the development of a viable laser ignition system are presented. The relative merits of various implementation strategies for laser based ignition are discussed. Finally, the performance improvements required for some of the components for successful field implementation are listed. Also reported are efforts to determine the relative merit of laser ignition over conventional Capacitance Discharge Ignition (CDI) ignition. Emissions and performance data of a large-bore single cylinder research engine are compared while running with laser ignition and the industry standard CDI system. It was primarily noticed that NOx emissions reduce by 50% under full load conditions with up to 65% reductions noticed under part load conditions. Also, the lean ignition limit was significantly extended and laser ignition improved combustion stability under all operating conditions. Other noticeable differences in combustion characteristics are also presented. Efforts wherein ignition was achieved while transmitting the high-power laser pulses through optical fibers showed performance improvements similar those achieved by using free-space laser ignition.

Improving the Efficiency of the Advanced Injection Low Pilot Ignited Natural Gas Engine Using Organic Rankine Cycles

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
K. K. Srinivasan ◽  
P. J. Mago ◽  
G. J. Zdaniuk ◽  
L. M. Chamra ◽  
K. C Midkiff
Keyword(s):  
Natural Gas ◽  
Conversion Efficiency ◽  
Waste Heat ◽  
Injection Timing ◽  
Base Line ◽  
Nox Emissions ◽  
Oxides Of Nitrogen ◽  
Fuel Conversion ◽  
Lean Combustion ◽  
Organic Rankine Cycles

Intense energy security debates amidst the ever increasing demand for energy in the US have provided sufficient impetus to investigate alternative and sustainable energy sources to the current fossil fuel economy. This paper presents the advanced (injection) low pilot ignition natural gas (ALPING) engine as a viable, efficient, and low emission alternative to conventional diesel engines, and discusses further efficiency improvements to the base ALPING engine using organic rankine cycles (ORC) as bottoming cycles. The ALPING engine uses advance injection (50–60deg BTDC) of very small diesel pilots in the compression stroke to compression ignite a premixed natural gas-air mixture. It is believed that the advanced injection of the higher cetane diesel fuel leads to longer in-cylinder residence times for the diesel droplets, thereby resulting in distributed ignition at multiple spatial locations, followed by lean combustion of the higher octane natural gas fuel via localized flame propagation. The multiple ignition centers result in faster combustion rates and higher fuel conversion efficiencies. The lean combustion of natural gas leads to reduction in local temperatures that result in reduced oxides of nitrogen (NOx) emissions, since NOx emissions scale with local temperatures. In addition, the lean premixed combustion of natural gas is expected to produce very little particulate matter emissions (not measured). Representative base line ALPING (60deg BTDC pilot injection timing) (without the ORC) half load (1700rpm, 21kW) operation efficiencies reported in this study are about 35% while the corresponding NOx emission is about 0.02g∕kWh, which is much lower than EPA 2007 Tier 4 Bin 5 heavy-duty diesel engine statutes of 0.2g∕kWh. Furthermore, the possibility of improving fuel conversion efficiency at half load operation with ORCs using “dry fluids” is discussed. Dry organic fluids, due to their lower critical points, make excellent choices for waste heat recovery Rankine cycles. Moreover, previous studies indicate that dry fluids are more preferable compared to wet fluids because the need to superheat the fluid to extract work from the turbine is eliminated. The calculations show that ORC—turbocompounding results in fuel conversion efficiency improvements of the order of 10% while maintaining the essential low NOx characteristics of ALPING combustion.

The Hybrid Rich-Burn/Lean-Burn Engine

1997 ◽  
Vol 119 (1) ◽  
pp. 243-249 ◽  
Author(s):  
D. P. Meyers ◽  
J. T. Kubesh
Keyword(s):  
Carbon Monoxide ◽  
Natural Gas ◽  
Combustion Stability ◽  
Lean Burn ◽  
Lean Mixture ◽  
Combustion Limits ◽  
Lean Limit ◽  
The Rich ◽  
Engine Concept ◽  
Combustion Exhaust

This paper describes a new low-emissions engine concept called the hybrid rich-burn/lean-burn (HRBLB) engine. In this concept a portion of the cylinders of a multicylinder engine are fueled with a very rich natural gas-air mixture. The remaining cylinders are operated with a lean mixture of natural gas and air and supplemented with the rich combustion exhaust. The goal of this unique concept is the production of extremely low NOx (e.g., 5 ppm when corrected to 15 percent exhaust oxygen content). This is accomplished by operating outside the combustion limits where NOx is produced. In rich combustion an abundance of hydrogen and carbon monoxide is produced. Catalyst treatment of the rich exhaust can be employed to increase the hydrogen concentration and decrease the carbon monoxide concentration simultaneously. The hydrogen-enriched exhaust is used to supplement the lean mixture cylinders to extend the lean limit of combustion, and thus produces ultralow levels of NOx. Results to date have shown NOx levels as low as 8 ppm at 15 percent oxygen can be achieved with good combustion stability and thermal efficiency.

The Advanced Low Pilot Ignited Natural Gas Engine: A Low NOx Alternative to the Diesel Engine

2003 ◽  
Author(s):  
Kalyan K. Srinivasan ◽  
Sundar R. Krishnan ◽  
Satbir Singh ◽  
K. Clark Midkiff ◽  
Stuart R. Bell ◽  
...  
Keyword(s):  
Natural Gas ◽  
Low Cost ◽  
Injection Timing ◽  
Nox Emissions ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Engine Stability ◽  
Unburned Hydrocarbons ◽  
Cylinder Compression ◽  
Diesel Operation

High nitrogen oxides (NOx) and particulate matter (PM) emissions restrict future use of conventional diesel engines for efficient, low-cost power generation. The advanced low pilot ignited natural gas (ALPING) engine described here has potential to meet stringent NOx and PM emissions regulations. It uses natural gas as the primary fuel (95 to 98 percent of the fuel energy input here) and a diesel fuel pilot to achieve compression ignition. Experimental measurements are reported from a single cylinder, compression-ignition engine employing highly advanced injection timing (45°–60°BTDC). The ALPING engine is a promising strategy to reduce NOx emissions, with measured full-load NOx emissions of less than 0.25 g/kWh and identical fuel economy to baseline straight diesel operation. However, unburned hydrocarbons were significantly higher for ALPING operation. Engine stability, as measured by COV, was 4–6 percent for ALPING operation compared to 0.6–0.9 percent for straight diesel.

NOx Emissions From a Diesel Engine Fueled With Natural Gas

1995 ◽  
Vol 117 (4) ◽  
pp. 290-296 ◽  
Author(s):  
Y. Tao ◽  
K. B. Hodgins ◽  
P. G. Hill
Keyword(s):  
Diesel Engine ◽  
Natural Gas ◽  
Ignition Delay ◽  
Substantial Reduction ◽  
Equilibrium Concentration ◽  
Nox Emission ◽  
Combustion Model ◽  
Injection Timing ◽  
Exhaust Pipe ◽  
Nox Emissions

The performance and emission characteristics of a single-cylinder two-stroke diesel engine fueled with direct injection of natural gas entrained with pilot diesel ignition enhancer have been measured. The thermal efficiency of the optimum gas-diesel operation was shown to exceed that of the conventional diesel at full load, but to be less at part load where the ignition delay was excessive. At high load, where the NOx emission problem is most serious, substantial reduction in NOx emission rate was obtained with delay of injection timing and also with use of exhaust gas recirculation. Measured cylinder pressures were used with a three-zone combustion model to determine ignition delay and the temperatures of the burned gas. The predicted NOx emissions based on equilibrium concentration of NO at the maximum burned gas temperature were found to correlate closely with exhaust pipe measurements of NOx.

Experimental Characterization of the Combustion in Fuel Flexible Humid Power Cycles

2021 ◽  
Author(s):  
Simeon Dybe ◽  
Felix Güthe ◽  
Michael Bartlett ◽  
Panagiotis Stathopoulos ◽  
Christian Oliver Paschereit
Keyword(s):  
Natural Gas ◽  
Equivalence Ratio ◽  
High Efficiency ◽  
Full Potential ◽  
Nox Emissions ◽  
Nox Formation ◽  
Fuel Blend ◽  
Power Cycles ◽  
Wide Range ◽  
Renewable Electricity Generation

Abstract Modified humid power cycles provide the necessary boundary condition for combustion to operate on a wide fuel spectrum in a steam-rich atmosphere comprising hydrogen and syngas from gasification besides natural gas as fuels. Thus, these cycles with their high efficiency and flexibility fit in a carbon-free energy market dominated by renewable electricity generation, providing dispatchable heat and electric power. To realize their full potential, the combustor utilized in such power cycles must fulfill the emission limits as well as demands of stable combustion over a wide range of fuel and steam ratios. The operation is limited by the risk of lean blowout for highly diluted syngas with low reactivity, and flashback for highly reactive hydrogen. Further, the gasification product gas can contain unwanted pollutants such as tars and nitrogen containing species like ammonia (NH3). Tars carry a considerable portion of the feedstock’s energy but are associated with detrimental operational behavior. The presence of ammonia in the combustion increases the risk of high NOx-emission at already small ammonia concentrations in the fuel. In this work, humid hydrogen flames are analyzed for their stability and emissions. Stable hydrogen flames were produced over a wide equivalence ratio and steam ratio range at negligible NOx-emissions. Further, natural gas, and a fuel blend substituting bio-syngas, was doped with ammonia. The combustion is analyzed with a focus on emissions and flame position and stability. The addition of ammonia causes high NOx-formation from fuel bound nitrogen (FBN), which highly increases NOx-emissions. The latter decrease with increasing NH3 content and increasing equivalence ratio.

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