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.

scholarly journals Research on Fuel Efficiency and Emissions of Converted Diesel Engine with Conventional Fuel Injection System for Operation on Natural Gas

Energies ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 2413 ◽  
Author(s):  
Lebedevas ◽  
Pukalskas ◽  
Daukšys ◽  
Rimkus ◽  
Melaika ◽  
...  
Keyword(s):  
Energy Efficiency ◽  
Natural Gas ◽  
Fuel Injection ◽  
Injection System ◽  
Dual Fuel ◽  
Injection Timing ◽  
Fuel Injection System ◽  
Significant Deterioration ◽  
Engine Operation ◽  
Conventional Fuel

This paper presents a study on the energy efficiency and emissions of a converted high-revolution bore 79.5 mm/stroke 95 mm engine with a conventional fuel injection system for operation with dual fuel feed: diesel (D) and natural gas (NG). The part of NG energy increase in the dual fuel is related to a significant deterioration in energy efficiency (ηi), particularly when engine operation is in low load modes and was determined to be below 40% of maximum continuous rating. The effectiveness of the D injection timing optimisation was established in high engine load modes within the range of a co-combustion ratio of NG ≤ 0.4: with an increase in ηi, compared to D, the emissions of NOx+ HC decreased by 15% to 25%, while those of CO2 decreased by 8% to 16%; the six-fold CO emission increase, up to 6 g/kWh, was unregulated. By referencing the indicated process characteristics of the established NG phase elongation in the expansion stroke, the combustion time increase as well as the associated decrease in the cylinder excess air ratio (α) are possible reasons for the increase in the incomplete combustion product emission.

Assessing Double Injection and Intake Air Temperature Effects on Gasoline HCCI Engine Performance and Emissions Using Fully-Automated Experiments and Micro-Genetic Algorithms

2002 ◽  
Author(s):  
Mustafa Canakci ◽  
Eric Hruby ◽  
Rolf D. Reitz
Keyword(s):  
Air Temperature ◽  
Gasoline Engine ◽  
Engine Performance ◽  
Operating Conditions ◽  
Spray Angle ◽  
Injection Timing ◽  
Engine Operation ◽  
Double Injection ◽  
Performance And Emissions ◽  
Engine Performance And Emissions

Homogeneous charge compression ignition (HCCI) is receiving attention as a new low emission engine concept. Little is known about the optimal operating conditions for this engine operation mode. Combustion at homogeneous, low equivalence ratio conditions results in modest temperature combustion products, containing very low concentrations of NOx and PM as well as providing high thermal efficiency. However, this combustion mode can produce higher HC and CO emissions than those of conventional engines. An electronically controlled Caterpillar single-cylinder oil test engine (SCOTE), originally designed for heavy-duty diesel applications, was converted to a HCCI direct-injection gasoline engine. The engine features an electronically controlled low-pressure common rail injector with a 60°-spray angle that is capable of multiple injections. The use of double injection was explored for emission control, and the engine was optimized using fully-automated experiments and a micro-genetic algorithm (μGA) optimization code. The variables changed during the optimization include the intake air temperature, start of injection timing, and split injection parameters (percent mass of the fuel in each injection, dwell between the pulses). The engine performance and emissions were determined at 700 rev/min with a constant fuel flow rate at 10 MPa fuel injection pressure. The results show that significant emissions reductions are possible with the use of optimal injection strategies.

scholarly journals A Numerical Study on the Pilot Injection Conditions of a Marine 2-Stroke Lean-Burn Dual Fuel Engine

Processes ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 1396
Author(s):  
Hao Guo ◽  
Song Zhou ◽  
Jiaxuan Zou ◽  
Majed Shreka
Keyword(s):  
Natural Gas ◽  
Fuel Injection ◽  
Numerical Study ◽  
Pollutant Emissions ◽  
Dual Fuel ◽  
Injection Timing ◽  
Pilot Injection ◽  
Lean Burn ◽  
Injection Duration ◽  
Pilot Fuel

The global demand for clean fuels is increasing in order to meet the requirements of the International Maritime Organization (IMO) of 0.5% global Sulphur cap and Tier III emission limits. Natural gas has begun to be popularized on liquefied natural gas (LNG) ships because of its low cost and environment friendly. In large-bore marine engines, ignition with pilot fuel in the prechamber is a good way to reduce combustion variability and extend the lean-burn limit. However, the occurrence of knock limits the increase in power. Therefore, this paper investigates the effect of pilot fuel injection conditions on performance and knocking of a marine 2-stroke low-pressure dual-fuel (LP-DF) engine. The engine simulations were performed under different pilot fuel parameters. The results showed that the average in-cylinder temperature, the average in-cylinder pressure, and the NOx emissions gradually decreased with the delay of the pilot injection timing. Furthermore, the combustion situation gradually deteriorated as the pilot injection duration increased. A shorter pilot injection duration was beneficial to reduce NOx pollutant emissions. Moreover, the number of pilot injector orifices affected the ignition of pilot fuel and the flame propagation speed inside the combustion chamber.

Stoichiometric Operation of a Gas Engine Utilizing Synthesis Gas and EGR for NOx Control

2000 ◽  
Vol 122 (4) ◽  
pp. 617-623 ◽  
Author(s):  
Jack A. Smith ◽  
Gordon J. J. Bartley
Keyword(s):  
Natural Gas ◽  
Synthesis Gas ◽  
Engine Performance ◽  
Constant Load ◽  
Nox Emissions ◽  
Fuel Reforming ◽  
Southwest Research Institute ◽  
Performance And Emissions ◽  
Nox Control ◽  
Engine Performance And Emissions

This paper presents the results from an internal research study conducted at the Southwest Research Institute (SwRI) on the effects of stoichiometric mixtures of natural gas and synthesis gas with exhaust gas recirculation (EGR) on engine performance and exhaust emissions. Constant load performance and emissions tests were conducted on a modified, single-cylinder, Caterpillar 1Y540 research engine at 11.0 bar (160 psi) bmep. Engine performance and emissions comparisons between natural gas with EGR, and natural gas with syngas and EGR are presented. In addition, the performance characteristics of the fuel reforming catalyst are presented. Results show that thermal efficiency increases with increasing EGR for both natural gas operation and natural gas with syngas operation at constant load. The use of syngas with natural gas extended the EGR tolerance by 44.4 percent on a mass basis compared to natural gas only, leading to a 77 percent reduction in raw NOx emissions over the lowest natural gas with EGR NOx emissions. [S0742-4795(00)00504-4]

Results and Experience From Operation and Testing of ALSTOM’s 30 MW GT10C Gas Turbine

2003 ◽  
Author(s):  
Anders Hellberg ◽  
Georg Norden ◽  
Mats Andersson ◽  
Thomas Widgren ◽  
Christer Hjalmarsson ◽  
...  
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Liquid Fuel ◽  
Engine Performance ◽  
Liquid Fuels ◽  
Critical Parameters ◽  
Test Rig ◽  
Load Range ◽  
Performance And Emissions ◽  
Inlet Conditions

ALSTOM’s new gas turbine, the GT10C, is a 30 MW industrial gas turbine for mechanical drive and power generation, which has been upgraded from the 25 MW GT10B. The thermal efficiency of the new gas turbine is 37.3% at ISO inlet conditions with no losses. The GT10C features a dual-fuel dry low emission gas turbine, with emissions values of 15 ppm NOx on gaseous fuel and 42 ppm NOX on liquid fuel (also dry). The GT10C was first started and operated on load in November 2001 and the test program is ongoing until the fall of 2002. The program covers a complete package test, including gas turbine, auxiliaries and control system, to ensure package availability. For the tests, a new test rig has been built in Finspong, Sweden, for testing on both natural gas and liquid fuels. The tests have been very successful, achieving the product targets, for example below 15 ppm NOx, without combustor pulsations. This paper discusses operation experience from the test rig, where the engine has been tested on both natural gas and liquid fuel over the whole load range. The engine has been equipped with over 1200 measuring points, covering the complete gas turbine. All critical parameters have been carefully verified in the test, such as turbine blade temperature and stresses, combustor temperatures and dynamics and engine performance. Results from the tests and measurements will be discussed in this paper. Performance and emissions will also be evaluated.

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.

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