A Potentiality of Dedicated EGR in SI Engines Fueled by Natural Gas for Improving Thermal Efficiency and Reducing NOx Emission

2014 ◽  
Vol 8 (1) ◽  
pp. 238-249 ◽  
Author(s):  
Sejun Lee ◽  
Kyohei Ozaki ◽  
Norimasa Iida ◽  
Takahiro Sako
Keyword(s):  
Natural Gas ◽  
Thermal Efficiency ◽  
Nox Emission ◽  
Si Engines

Development of Low NOx Combustion Technology in Medium-Btu Fueled 1300 °C-Class Gas Turbine Combustor in IGCC

2000 ◽  
Author(s):  
Takeharu Hasegawa ◽  
Tohru Hisamatsu ◽  
Yasunari Katsuki ◽  
Mikio Sato ◽  
Hiromi Koizumi ◽  
...  
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Thermal Efficiency ◽  
Nox Emission ◽  
Test Results ◽  
Nitrogen Injection ◽  
Coal Gasifier ◽  
Coal Fuel ◽  
Thermal Nox ◽  
Low Nox Emission

The development of integrated coal gasification combined cycle (IGCC) systems ensures higher thermal efficiency and environmentally sound options for supplying future coal utilizing power generation needs. The Japanese government and electric power industries in Japan promoted research and development of an IGCC system using an air-blown entrained-flow coal gasifier. On the other hand, Europe and the United States are now developing the oxygen-blown IGCC demonstration plants. Gasified coal fuel produced in an oxygen-blown entrained-flow coal gasifier, has a calorific value of 8–13MJ/m3 which is only 1/5–1/3 that of natural gas. However, the flame temperature of medium-Btu gasified coal fuel is higher than that of natural gas and so NOx production from nitrogen fixation is expected to increase significantly. In the oxygen-blown IGCC, a surplus nitrogen produced in the air-separation unit (ASU) is premixed with gasified coal fuel (medium-Btu fuel) and injected into the combustor, to reduce thermal-NOx production and to recover the power used for the ASU. In this case, the power to compress nitrogen increases. Low NOx emission technology which is capable of decreasing the power to compress nitrogen is a significant advance in gas turbine development with an oxygen-blown IGCC system. Analyses confirmed that the thermal efficiency of the plant improved by approximately 0.3 percent (absolute) by means of nitrogen direct injection into the combustor, compared with a case where nitrogen is premixed with gasified coal fuel before injection into the combustor. In this study, based on the fundamental test results using a small diffusion burner and a model combustor, we designed the combustor in which the nitrogen injection nozzles arranged on the burner were combined with the lean combustion technique for low-NOx emission. In this way, we could reduce the high temperature region, where originated the thermal-NOx production, near the burner positively. And then, a combustor with a swirling nitrogen injection function used for a gas turbine, was designed and constructed, and its performance was evaluated under pressurized conditions of actual operations using a simulated gasified coal fuel. From the combustion test results, the thermal-NOx emission decreased under 11ppm (corrected at 16% O2), combustion efficiency was higher than 99.9% at any gas turbine load. Moreover, there was different effects of pressure on thermal-NOx emission in medium-Btu fuel fired combustor from the case of natural gas fired combustor.

scholarly journals A Potentiality of Dedicated EGR System for Improving Thermal Efficiency in Natural Gas SI Engines

2015 ◽  
Vol 6 (1) ◽  
pp. 15-22
Author(s):  
Lee Sejun ◽  
Kyohei Ozaki ◽  
Takahiro Sako ◽  
Norimasa Iida
Keyword(s):  
Natural Gas ◽  
Thermal Efficiency ◽  
Si Engines

Power Cycles of Generation III and III+ Nuclear Power Plants

2014 ◽  
Author(s):  
Alexey Dragunov ◽  
Eugene Saltanov ◽  
Igor Pioro ◽  
Pavel Kirillov ◽  
Romney Duffey
Keyword(s):  
Renewable Energy ◽  
Natural Gas ◽  
Thermal Efficiency ◽  
Nuclear Power ◽  
Power Plants ◽  
Renewable Energy Sources ◽  
Thermal Power ◽  
Electrical Energy ◽  
Energy Sources ◽  
Thermal Power Plants

It is well known that the electrical-power generation is the key factor for advances in any other industries, agriculture and level of living. In general, electrical energy can be generated by: 1) non-renewable-energy sources such as coal, natural gas, oil, and nuclear; and 2) renewable-energy sources such as hydro, wind, solar, biomass, geothermal and marine. However, the main sources for electrical-energy generation are: 1) thermal - primary coal and secondary natural gas; 2) “large” hydro and 3) nuclear. The rest of the energy sources might have visible impact just in some countries. Modern advanced thermal power plants have reached very high thermal efficiencies (55–62%). In spite of that they are still the largest emitters of carbon dioxide into atmosphere. Due to that, reliable non-fossil-fuel energy generation, such as nuclear power, becomes more and more attractive. However, current Nuclear Power Plants (NPPs) are way behind by thermal efficiency (30–42%) compared to that of advanced thermal power plants. Therefore, it is important to consider various ways to enhance thermal efficiency of NPPs. The paper presents comparison of thermodynamic cycles and layouts of modern NPPs and discusses ways to improve their thermal efficiencies.

Decreasing hydrocarbon and carbon monoxide emissions of a natural-gas engine operating in the quasi-homogeneous charge compression ignition mode at low loads

2005 ◽  
Vol 219 (9) ◽  
pp. 1125-1131 ◽  
Author(s):  
Su Ling ◽  
Zhou Longbao ◽  
Liu Shenghua ◽  
Zhong Hui
Keyword(s):  
Carbon Monoxide ◽  
Natural Gas ◽  
Thermal Efficiency ◽  
Homogeneous Charge Compression Ignition ◽  
Compression Ignition ◽  
Brake Thermal Efficiency ◽  
Pilot Fuel ◽  
Cng Engine ◽  
Standard Mode ◽  
Homogeneous Charge

Experimental studies have been carried out on decreasing the hydrocarbon (HC) and carbon monoxide (CO) emissions of a compressed natural-gas (CNG) engine operating in quasi-homogeneous charge compression ignition (QHCCI) mode at low loads. The effects of three technical approaches including partial gas cut-off (PGC), intake air throttling, and increasing the pilot fuel quantity on emissions and the brake thermal efficiency of the CNG engine are studied. The results show that HC and CO emissions can be reduced with only a small penalty on the brake thermal efficiency. An increase in the brake thermal efficiency and reductions in HC and CO emissions can be simultaneously realized by increasing the pilot fuel quantity. It is also indicated from experiments that the HC and CO emissions of the engine can be effectively reduced when using intake air throttling and increasing the pilot fuel quantity are both adopted. However, nitrogen oxide (NOx) emissions increase with increase in the throttling and the pilot fuel quantity. Under PGC conditions, NOx emissions are lower than those in the standard mode; however, they increase and exceed the values in the standard mode in increases in the load and natural-gas supply.

Application of Reburning for NOx Control to a Firetube Package Boiler

1985 ◽  
Vol 107 (3) ◽  
pp. 739-743 ◽  
Author(s):  
J. A. Mulholland ◽  
W. S. Lanier
Keyword(s):  
Natural Gas ◽  
Reaction Order ◽  
Nox Reduction ◽  
Process Variable ◽  
Nox Emission ◽  
Boiler Load ◽  
Second Stage ◽  
Primary Zone ◽  
Dominant Process ◽  
Nox Control

A 730 kW (2.5 × 106 Btu/hr) firetube package boiler was used to demonstrate the application of reburning for NOx emission control. An overall reduction of 50 percent from an uncontrolled NOx emission of 200 ppm was realized by diverting 15 percent of the total boiler load to a natural-gas-fired second stage burner. Tests indicate that the overall reaction order of destruction with respect to initial NOx is greater than one; thus, larger reductions can be expected from reburning applications to systems with higher initial NOx. Rich zone stoichiometry has been identified as the dominant process variable. Primary zone stoichiometry and rich zone residence time are parameters that can be adjusted to maximize NOx reduction. Reburning applied to firetube package boilers requires minimal facility modification. Natural gas would appear to be an ideal reburning fuel as nitrogen in the reburning fuel has been shown to inhibit NOx reduction.

scholarly journals Fundamental Study on Combustion Improvement by Mixture-Flow in Natural Gas-Fueled Lean-Burn SI Engines

2000 ◽  
Vol 35 (4) ◽  
pp. 254-259
Author(s):  
Daisuke Segawa ◽  
Toshikazu Kadota ◽  
Masashi Ohno ◽  
Takeshi Mizobuchi ◽  
Katsumi Kataoka ◽  
...  
Keyword(s):  
Natural Gas ◽  
Lean Burn ◽  
Mixture Flow ◽  
Fundamental Study ◽  
Si Engines ◽  
Gas Fueled

A Study on In-Cylinder Injection of Low Pressure Natural Gas for Performance Improvement of Small Sized Two-Stroke SI Engines

2001 ◽  
Author(s):  
Shiyuji Hatakeyama ◽  
Yoshio Sekiya ◽  
Tadashi Murayama ◽  
Shunsaku Nakai ◽  
Takahiro Sako ◽  
...  
Keyword(s):  
Natural Gas ◽  
Performance Improvement ◽  
Low Pressure ◽  
Si Engines

Operating Characteristics of Natural Gas Fueled Homogeneous Charge Compression Ignition Engine

1999 ◽  
Author(s):  
Y. Kawabata ◽  
K. Nakagawa ◽  
F. Shoji
Keyword(s):  
Natural Gas ◽  
Homogeneous Charge Compression Ignition ◽  
Nox Emission ◽  
Compression Ignition ◽  
Operating Characteristics ◽  
Compression Ignition Engine ◽  
Gas Engine ◽  
Engine Combustion ◽  
Gas Fueled ◽  
Homogeneous Charge

Abstract Recently, a new design of engine combustion that achieves higher efficiency and less NOx emission has been proposed. Some researchers have started studying the concept, which is called Homogeneous Charge Compression Ignition (HCCI), but there have been few reports on investigations using a future prospective alternative fuel, natural gas. In this study, natural gas fueled operation of HCCI using a single cylinder gas engine was conducted. Operating and exhaust characteristics were obtained. Experimental data confirmed the potential of higher efficiency and less NOx emission, though THC and CO were higher. Based on these data, the feasibility of this concept for gas engines is also examined.

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