scholarly journals NOx Emission Characteristics of a Catalytic Combustor Under High-Temperature Conditions

1995 ◽  
Author(s):  
Martin Valk ◽  
Nicolas Vortmeyer ◽  
Günter Kappler
Keyword(s):  
High Temperature ◽  
Flame Temperature ◽  
Plug Flow ◽  
Nox Emission ◽  
Thermal Reactor ◽  
Emission Characteristics ◽  
Nox Emissions ◽  
Temperature Conditions ◽  
Conversion Rates ◽  
Catalytic Combustor

A catalytic combustor concept with short catalyst segments and a thermal reactor is investigated with regard to NOx production of this concept under high-temperature conditions. The maximum combustor exit temperature was more than 1800 K with catalyst temperatures below 1300 K. For combustion of iso-octane, NOx emissions of 4 ppm (dry, 15% O2) at a flame temperature of 1800 K were measured. No significant influence of catalyst length, reference velocity and overall residence time on NOx emissions was observed. Additionally, the test combustor was fuelled with commercial diesel and kerosene (Jet-A). In this case, NOx emissions were noticeable higher due to fuel-bound nitrogen. The emissions measured were for diesel, 12 ppm, and for kerosene, 7 ppm, (each dry, 15% O2), again at a flame temperature of 1800 K. To evaluate the conversion ratio of fuel-bound nitrogen to NOx iso-octane was doped with various amounts of ammonia and metyhlamine. The conversion rates were 70 to 90%, with a slight tendency to lower values (50%) for nitrogen mass fractions above 0.1%. Considering the NOx emission level of actual premix burners, the lower emission value of the presented catalytic combustor results from a perfect premixed plug-flow combustion system incorporating a catalyst herein and not from a specific advantage of the principle of catalytic combustion itself. Again similar to a premix-combustor are the NOx emission characteristics in the case of lean combustion of nitrogen bound fuels, which yield very high conversion rates.

The Effect of Distance Between Fuel and Oxidizer Nozzles on NOx Emission From High Temperature Air Combustion

2011 ◽  
Author(s):  
Yuzuru Nada ◽  
Yasutomo Zenman ◽  
Takahiro Ito ◽  
Susumu Noda
Keyword(s):  
High Temperature ◽  
Flame Temperature ◽  
Dilution Effect ◽  
Nox Emission ◽  
Emission Characteristics ◽  
High Temperature Air Combustion ◽  
Flamelet Model ◽  
Scaling Parameters ◽  
Fuel Nozzle ◽  
Emission Index

This study describes NOx emission characteristics of a high temperature air combustion furnace operating with parallel jet burner system. In the parallel jet burner system, fuel nozzles are separated with a distance from an oxidizer nozzle. Objectives of this study are to clarify the effect of the distance between the fuel nozzle and the oxidizer nozzle on NOx emission. The emission index of NOx (EINOx) decreases with the increase in the distance. This is due to the dilution through entrainment of burned gas. A scaling concept is proposed to assess the dilution effect on the NOx emission. Scaling parameters employed here are the global residence time of fuel and the flame temperature evaluated on a modified flamelet model in which the dilution effect is included. The overall EINOx production rate is scaled with the flame temperature. This scaling indicates the importance of the distance between the nozzles for NOx emission.

A Catalytic Combustor for High-Temperature Gas Turbines

1996 ◽  
Vol 118 (1) ◽  
pp. 61-64 ◽  
Author(s):  
N. Vortmeyer ◽  
M. Valk ◽  
G. Kappler
Keyword(s):  
High Temperature ◽  
Gas Turbines ◽  
Essential Feature ◽  
Research Work ◽  
Thermal Reactor ◽  
Experimental Investigations ◽  
Phase Reaction ◽  
Catalyst Temperature ◽  
Catalytic Combustor ◽  
High Temperature Gas

Catalytic combustion has been the subject of thorough research work for over two decades, mainly in the U.S. and Japan. However, severe material problems in the ceramic or metallic monolith prevented regular operation in most cases. Still, during these two decades, turbine inlet temperatures were raised remarkably, and lean premix combustors have become standard in stationary gas turbines. In view of these facts, a simple “monolith-in-tube” concept of a catalytic combustor was adapted for the use in high-temperature gas turbines. Its essential feature is the fact that a considerable portion of the homogeneous gas phase reaction is shifted to the thermal reactor, thus lowering the catalyst temperature. This is achieved by the employment of very short catalyst segments. The viability of this concept has been demonstrated for a variety of pure hydrocarbons, alcohols as well as common liquid fuels. Extensive experimental investigations of the atmospheric combustor led to the assessment of parameters such as reference velocity, fuel-to-air ratio, and fuel properties. The maximum combustor exit temperature was 1673 K with a corresponding catalyst temperature of less than 1300 K for diesel fuel. Boundary conditions were in all cases combustion efficiency (over 99.9 percent) and pressure loss (less than 6 percent). Additionally, a model has been developed to predict the characteristic values of the catalytic combustor such as necessary catalyst length, combustor volume, and emission characteristics. The homogeneous reaction in the thermal reactor can be calculated by a one-dimensional reacting flow model.

Effect of Fuel Staged Proportion on NOX Emission Performance of Centrally Staged Combustor

2013 ◽  
Author(s):  
Fuqiang Liu ◽  
Yong Mu ◽  
Cunxi Liu ◽  
Jinhu Yang ◽  
Yanhui Mao ◽  
...  
Keyword(s):  
Equivalence Ratio ◽  
Flow Reactor ◽  
Flame Temperature ◽  
Plug Flow ◽  
Combustion Process ◽  
Chemical Reactor ◽  
Nox Emission ◽  
Wide Range ◽  
Pilot Fuel ◽  
Pollution Emissions

The low NOX emission technology has become an important feature of advanced aviation engine. A wide range of applications attempt to take advantage of the fact that staged combustion operating under lean-premixed-prevaporized (LPP) conditions can significantly decrease pollution emissions and improve combustion efficiency. In this paper a scheme with fuel centrally staged and multi-point injection is proposed. The mixing of fuel and air is improved, and the flame temperature is typically low in combustion zone, minimizing the formation of nitrogen oxides (NOX), especially thermal NOX. In terms of the field distribution of equivalence ratio and temperature obtained from Computational Fluid Dynamics (CFD), a chemical reactor network (CRN), including several different ideal reactor, namely perfectly stirred reactor (PSR) and plug flow reactor (PFR), is constructed to simulate the combustion process. The influences of the pilot equivalence ratio and percentage of pilot/main fuel on NOX and carbon monoxide (CO) emissions were studied by Chemical CRN model. Then the NOX emission in the staged combustor was researched experimentally. The effects of the amount of pilot fuel and primary fuel on pollution emissions were obtained by using gas analyzer. Finally, the effects of pilot fuel proportion on NOX emission were discussed in detail by comparing predicts of CRN and experimental results.

scholarly journals A Catalytic Combustor for High-Temperature Gas Turbines

1994 ◽  
Author(s):  
Nicolas Vortmeyer ◽  
Martin Valk ◽  
Günter Kappler
Keyword(s):  
High Temperature ◽  
Gas Turbines ◽  
Essential Feature ◽  
Research Work ◽  
Thermal Reactor ◽  
Experimental Investigations ◽  
Phase Reaction ◽  
Catalyst Temperature ◽  
Catalytic Combustor ◽  
High Temperature Gas

Catalytic combustion has been the subject of thorough research work for over two decades, mainly in the U.S. and Japan. However, severe material problems in the ceramic or metallic monolith prevented regular operation in most cases. Still, during these two decades, turbine inlet temperatures were raised remarkably, and lean premix combustors have become standard in stationary gas turbines. In view of these facts, a simple “monolith-in-tube” concept of a catalytic combustor was adapted for the use in high-temperature gas turbines. Its essential feature is the fact that a considerable portion of the homogeneous gas phase reaction is shifted to the thermal reactor, thus lowering the catalyst temperature. This is achieved by the employment of very short catalyst segments. The viability of this concept has been demonstrated for a variety of pure hydrocarbons, alcohols as well as common liquid fuels. Extensive experimental investigations of the atmospheric combustor lead to the assessment of parameters such as reference velocity, fuel-to-air ratio and fuel properties. The maximum combustor exit temperature was 1,673 K with a corresponding catalyst temperature of less than 1,300 K for Diesel fuel. Boundary conditions were in all cases combustion efficiency (over 99.9%) and pressure loss (less than 6%). Additionally, a model has been developped to predict the characteristic values of the catalytic combustor such as necessary catalyst length, combustor volume and emission characteristics. The homogeneous reaction in the thermal reactor can be calculated by a one-dimensional reacting flow model.

Full Scale Testing of a Cluster Nozzle Burner for the Advanced Humid Air Turbine

2007 ◽  
Author(s):  
Tomomi Koganezawa ◽  
Keisuke Miura ◽  
Takeo Saito ◽  
Kazuki Abe ◽  
Hiroshi Inoue
Keyword(s):  
High Temperature ◽  
Gas Turbine ◽  
Pilot Plant ◽  
Flame Temperature ◽  
Nox Emission ◽  
Flame Stability ◽  
High Humidity ◽  
Humidity Condition ◽  
Air Turbine ◽  
High Humidity Condition

The advanced humid air turbine (AHAT) system, which has a humidifier and a heat recovery system has the advantage of improving the thermal efficiency of gas turbine power generation without needing an extremely high firing temperature and pressure ratio. A pilot plant and a prototype gas turbine adapted to the AHAT system have been developed. Before the pilot plant test, an experimental study using a combustion test rig was carried out to obtain the characteristics of a prototype combustor and it is described in this presentation. The combustion conditions in the AHAT system are characterized by both high humidity and high temperature air (17.6wt%, 629C). It is expected that a low flame temperature caused by the high humidity condition will decrease NOx emission while the high temperature air condition will sustain flame stability. However, the latter condition has the disadvantage of causing NOx emission and autoignition of fuel. A cluster nozzle burner configuration, which has many fuel and air coaxial jet streams, was previously proposed. The cluster nozzle burner can mix fuel and air effectively within a short time which makes it suited to the AHAT system and able to cope with both flame stability and NOx reduction problems. The combustion rig test results showed good combustion performance for the developed cluster nozzle burner. Both the high temperature condition of the AHAT system and the recirculation zone generated by swirling of center burner air sustained flame stability at a level sufficient for the nozzle burner in AHAT operation. The low flame temperature due to the high humidity condition was effective in decreasing NOx emission, which was less than 10ppm at 50-100% load.

High Pressure Test Results of a Catalytic Combustor for Gas Turbine

1998 ◽  
Vol 120 (3) ◽  
pp. 509-513 ◽  
Author(s):  
T. Fujii ◽  
Y. Ozawa ◽  
S. Kikumoto ◽  
M. Sato ◽  
Y. Yuasa ◽  
...  
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Catalytic Combustion ◽  
Combustion Process ◽  
Combined Cycle ◽  
Nox Emission ◽  
Test Results ◽  
Catalytic Combustor

Recently, the use of gas turbine systems, such as combined cycle and cogeneration systems, has gradually increased in the world. But even when a clean fuel such as LNG (liquefied natural gas) is used, thermal NOx is generated in the high temperature gas turbine combustion process. The NOx emission from gas turbines is controlled through selective catalytic reduction processes (SCR) in the Japanese electric industry. If catalytic combustion could be applied to the combustor of the gas turbine, it is expected to lower NOx emission more economically. Under such high temperature and high pressure conditions, as in the gas turbine, however, the durability of the catalyst is still insufficient. So it prevents the realization of a high temperature catalytic combustor. To overcome this difficulty, a catalytic combustor combined with premixed combustion for a 1300°C class gas turbine was developed. In this method, catalyst temperature is kept below 1000°C, and a lean premixed gas is injected into the catalytic combustion gas. As a result, the load on the catalyst is reduced and it is possible to prevent the catalyst deactivation. After a preliminary atmospheric test, the design of the combustort was modified and a high pressure combustion test was conducted. As a result, it was confirmed that NOx emission was below 10 ppm (at 16 percent O2) at a combustor outlet gas temperature of 1300°C and that the combustion efficiency was almost 100 percent. This paper presents the design features and test results of the combustor.

scholarly journals High Pressure Test Results of a Catalytic Combustor for Gas Turbine

1996 ◽  
Author(s):  
T. Fujii ◽  
Y. Ozawa ◽  
S. Kikumoto ◽  
M. Sato ◽  
Y. Yuasa ◽  
...  
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Catalytic Combustion ◽  
Combustion Process ◽  
Combined Cycle ◽  
Nox Emission ◽  
Test Results ◽  
Catalytic Combustor

Recently, use of gas turbine systems such as combined cycle and cogeneration systems has gradually increased in the world. But even when a clean fuel such as LNG (liquefied natural gas) is used, thermal NOx is generated in the high temperature gas turbine combustion process. The NOx emission from gas turbines is controlled through selective catalytic reduction processes (SCR) in the Japanese electric industry. If catalytic combustion could be applied to the combustor of the gas turbine, it is expected to lower NOx emission more economically. Under such high temperature and high pressure conditions as in the gas turbine, however, the durability of the catalyst is still insufficient. So it prevents the realization of a high temperature catalytic combustor. To overcome this difficulty, a catalytic combustor combined with premixed combustion for a 1300°C class gas turbine was developed. In this method, catalyst temperature is kept below 1000°C and a lean premixed gas is injected into the catalytic combustion gas. As a result, the load on the catalyst is reduced and it is possible to prevent the catalyst deactivation. After a preliminary atmospheric test, the design of the combustor was modified and a high pressure combustion test was conducted. As a result, it was confirmed that NOx emission was below 10ppm (at 16% O2) at a combustor outlet gas temperature of 1300°C and that the combustion efficiency was almost 100%. This paper presents the design features and test results of the combustor.

scholarly journals Variations in the NOx Emission of Gas Turbines: Effects of Air Temperature, Air Humidity and Natural Gas Composition

1994 ◽  
Author(s):  
B. Martien Visser ◽  
Fred C. Bahlmann
Keyword(s):  
Gas Turbines ◽  
Flame Temperature ◽  
Calorific Value ◽  
Nox Emission ◽  
Nox Emissions ◽  
Gas Composition ◽  
Air Humidity ◽  
Ambient Conditions ◽  
Fuel Gas ◽  
Natural Gases

The NOx emission, produced by gas turbines varies with ambient conditions and with fuel gas composition. Often, legislation requires that the NOx emissions of gas turbines has to be corrected to standard conditions. The EPA formula may be used for the correction for ambient temperature and humidity. In the Netherlands, the correction for fuel-gas composition is based on the observation that for natural gases, NOx emission varies linearly with the Lower Calorific Value (LCV). It is concluded that both the EPA and LCV correction formulas are equivalent to the following relation between flame temperature and NOx emission: NOxa=NOxb*(1.0065)Ta−Tb where Ta and Tb represent characteristic flame temperatures under conditions a and b. In the paper, the utility of the EPA and the LCV correction formulas for gas turbines equipped with modem lean-premixed combustors is discussed.

Sign in / Sign up

Export Citation Format

Share Document