Development of a wide range-operable, rich-lean low-NOx combustor for NH3 fuel gas-turbine power generation

Kurata, Osamu; Iki, Norihiko; Inoue, Takahiro; Matsunuma, Takayuki; Tsujimura, Taku; Furutani, Hirohide; Kawano, Masato; Arai, Keisuke; Okafor, Ekenechukwu C.; Hayakawa, Akihiro; Kobayashi, Haruo

doi:10.1016/j.proci.2018.09.012

Cited by 182 publications

(64 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…3 More recent investigations [48][49][50] have achieved some success in stabilizing ammonia-air flames in simplified laboratory models of gas-turbine combustors while, at the same time, reducing NO x and N 2 O emissions to values closer to the regulatory limits. Early studies have illustrated, already several decades ago, some of the challenges emerging by substitution of ammonia to hydrocarbon fuels in gas turbines, due to the low reactivity and poor combustion characteristics of ammonia.…”

Section: Combustion Behavior Of Ammonia-derived Fuels and Comparison mentioning

confidence: 99%

“…Early studies have illustrated, already several decades ago, some of the challenges emerging by substitution of ammonia to hydrocarbon fuels in gas turbines, due to the low reactivity and poor combustion characteristics of ammonia. 3 More recent investigations [48][49][50] have achieved some success in stabilizing ammonia-air flames in simplified laboratory models of gas-turbine combustors while, at the same time, reducing NO x and N 2 O emissions to values closer to the regulatory limits. These advances have, however, been attained at the cost of a considerable increase of the fuel-air equivalence ratio (beyond stoichiometry) and of the residence time inside the combustion chamber, thereby raising possible issues with ammonia slip and reducing the fuel flexibility (fuel-switching capabilities) of the combustion system, respectively.…”

Section: Combustion Behavior Of Ammonia-derived Fuels and Comparison mentioning

confidence: 99%

See 1 more Smart Citation

An updated short chemical‐kinetic nitrogen mechanism for carbon‐free combustion applications

et al. 2019

View full text Add to dashboard Cite

Chemical-kinetic combustion mechanisms for hydrogen-oxygen-nitrogen systems, motivated originally by concerns about NO x emissions during hydrogen burning, have recently acquired renewed interest as a result of the possibility of employing ammonia-hydrogen mixtures in gas turbines and reciprocating engines as drop-in fuel to replace the use of natural gas. Specifically, this is of relevance to the implementation of engineering approaches for economical power generation with carbon sequestration or to large-scale energy-storage schemes, based on hydrogen or efficient hydrogen carriers such as ammonia. Because computational investigations are facilitated by short mechanisms (since the use of large mechanisms is often prohibitively expensive in reactive flow simulations), in response to the original concerns, a short nitrogen mechanism was developed in San Diego in the 1990s (not updated since 2004), without consideration of ammonia combustion. In view of the renewed interest in this topic, that mechanism has now been expanded to encompass 60 elementary steps among 19 reactive chemical species, including ammonia burning and NO x production, as reported herein, greatly improving predictions. With particular attention to high reactant temperatures and high-pressure conditions, relevant to industrial applications, it is shown that the present short mechanism retains satisfactory accuracy, exhibiting deviations that in most cases are within acceptable bounds (±20%). The revisions maintain the shortness of the original mechanism, adding only one more reactive species and six more elementary steps (while updating values of rate parameters of nine other steps, on the basis of newly available information). In addition, the short mechanism is applied herein to the analysis of fundamental combustion properties of ammonia/hydrogen/nitrogen-air laminar premixed flames, at unstrained and strained conditions, for comparison with methane-air flames as a reference gas-turbine fuel. It is found by comparing carbon-free and hydrocarbon laminar flames that these reactive mixtures, even if characterized by nearly identical adiabatic flame temperature and laminar flame speeds, nevertheless exhibit substantially different resistance to strain, with the ammonia/hydrogen flames exceeding the strain limit of methane flames by a factor of 5.

show abstract

Section: Combustion Behavior Of Ammonia-derived Fuels and Comparison mentioning

confidence: 99%

Section: Combustion Behavior Of Ammonia-derived Fuels and Comparison mentioning

confidence: 99%

An updated short chemical‐kinetic nitrogen mechanism for carbon‐free combustion applications

et al. 2019

View full text Add to dashboard Cite

show abstract

“…However, the prototype low-NOx combustor is not suitable for long time operation of the micro gas turbine due to starting-up procedure. AIST, Toyota Energy Solutions Inc. and Tohoku University manufactured the new low-NOx combustor (Step1) and actual power generation was performed (Kurata, O. et al, 2019) . In order to avoid destruction of the gas turbine, it is necessary to modify on the cooling structure of the combustor step by step.…”

Section: Low-nox Combustionmentioning

confidence: 99%

Rich-Lean Combustor for a 50kW class Micro Gas Turbine Firing Ammonia

Iki¹,

Kurata²,

Inoue³

et al. 2019

Proceedings of Global Power &Amp; Propulsion Society

Self Cite

View full text Add to dashboard Cite

Hydrogen production is expected as the useful energy storage technology for fluctuation of renewable energy. Ammonia is expected to be a hydrogen carrier that has potential as a carbon-free fuel. Ammonia is known as a nonignitable fuel, and it is not easy to hold ammonia flames under atmospheric conditions. A demonstration test with the aim of showing the potential of ammonia-fired power plants was conducted using a micro gas turbine. A 50-kW-class turbine system firing kerosene was selected as a base model. More than 40 kW of power generation was achieved by firing ammonia gas or a mixture of ammonia and methane by modifying the combustor, the fuel control device, and the gas turbine start-up sequence. The prototype bi-fuel combustor is a swirl combustor employing a non-premixed flame and a decreased air flow rate near a gas fuel injector for flame holding. Ammonia combustion in the prototype bi-fuel combustor was enhanced by supplying hot combustion air and by modifying the air inlets. However, the exhaust gases from the ammonia flames had high NOx concentrations. NOx removal equipment using selective catalytic reduction can reduce NOx emission levels to below 10 ppm from more than 1,000 ppm (converted value of NOx to 15% O2) as already reported. However, downsizing of NOx removal equipment should be achieved for practical use. Therefore, a low NOx combustor was developed. We modified the combustor to the rich-lean burning method and found the condition that the NO emission can be reduced to less than half, but the NOx emission reduction was insufficient as compared with the small-scale flow test at the lab scale. Therefore, each part of the combustor was redesigned so that mixing of fuel and air improves uniformity. Low-NOx combustor (Step2) was designed using knowledge of Prototype bi-fuel combustor for ammonia (Step0) and Low-NOx combustor (Step1). As a result, we found a condition that the NO emission can be reduced to 1/4 or less as compared with before redesigning for rich-lean combustion.

show abstract

“…They worked with a 50 kW-class micro gas-turbine firing NH 3 and kerosene and succeeded in generating electricity for the first time in the world. Later, Okafor et al (2019b) and Kurata et al (2017Kurata et al ( , 2019 improved the RL combustor to achieve lower emission. The RL combustor is similar to the rich quench lean (RQL) combustor (Lefebvre and Ballal, 2010) used in aviation or emergency gas turbines, but equivalence ratio in the rich zone of the RL combustor is closer to stoichiometric condition compared with the RQL combustor.…”

Section: Introductionmentioning

confidence: 99%

“…The volume is about 8 times that of the micro gas-turbine used in previous studies (Iki et al, 2015;Kurata et al, 2017Kurata et al, , 2019. An average value of each exhaust gas component in the radial direction at the liner outlet is sampled with a straight tube probe, which has nine sampling holes in the radial direction.…”

Section: Introductionmentioning

confidence: 99%

Emission characteristics of a lean-premixed ammonia/natural-gas gas-turbine combustor and effect of secondary ammonia injection

Ito

Uchida

Katō

et al. 2019

Mechanical Engineering Journal

Self Cite

View full text Add to dashboard Cite

To develop an NH 3 /natural gas-fired gas-turbine combustor with minimal modifications to a natural gas-fired combustor, the effect of co-firing NH 3 with natural gas on emission characteristics and combustion efficiency is investigated experimentally under atmospheric pressure. In this experiment, a lean premixed combustor that has basically the same structure and same size as those of an actual 2 MW-class gas-turbine combustor is used and the effects of equivalence ratio, NH 3 mixing ratio, and NH 3 injection method were evaluated. The results of NH 3 /natural gas/air premixed combustion show that NO emission shows a local maximum at a certain NH 3 mixing ratio, when equivalence ratio is fixed. The NH 3 mixing ratio where this maximal NO emission occurs shifts to higher ratios, when equivalence ratio is increased towards stoichiometric condition. At the same time, the maximal NO emission increases. The variation of NO x concentration can be explained by the change in the selective non-catalytic reduction (SNCR) effect, which depends on temperature and NH 3 concentration in the flame. In particular, the influence of NH 3 concentration on the SNCR effect appears to be stronger than that of temperature. On the other hand, concentrations of N 2 O and unburnt NH 3 increase with increasing NH 3 mixing ratio in the very lean case, when decreasing flame temperature approaches the lean flame blow-off limit. When NH 3 is directly injected into the lean premixed flame of natural gas, NO and N 2 O concentrations are simultaneously reduced; this is attributed to the local increase of NH 3 concentration and flame temperature. Finally, it is proposed to consider NO x as unburnt component in the calculation of combustion efficiency. When NH 3 is fired, the enthalpy content of NO x is very high, and its influence on combustion efficiency cannot be ignored. It is also found that NH 3 direct injection is effective in increasing combustion efficiency, achieving more than 99.6% of the combustion efficiency even if the enthalpy of NO x is considered.

show abstract

Development of a wide range-operable, rich-lean low-NOx combustor for NH3 fuel gas-turbine power generation

Cited by 182 publications

References 14 publications

An updated short chemical‐kinetic nitrogen mechanism for carbon‐free combustion applications

An updated short chemical‐kinetic nitrogen mechanism for carbon‐free combustion applications

Rich-Lean Combustor for a 50kW class Micro Gas Turbine Firing Ammonia

Emission characteristics of a lean-premixed ammonia/natural-gas gas-turbine combustor and effect of secondary ammonia injection

Contact Info

Product

Resources

About