Get the Most Out of Your Gas Turbine SCR NOx Abatement System

2003 ◽  
Author(s):  
Martin F. Collins ◽  
S. Mario DeCorso ◽  
David L. Moen
Keyword(s):  
Catalytic System ◽  
System Performance ◽  
Catalytic Reduction ◽  
Exhaust Gas ◽  
Scr Catalyst ◽  
Equipment Operation ◽  
Scr System ◽  
Scr Of Nox ◽  
Design Construction ◽  
Turbine Exhaust

Selective catalytic reduction (SCR) of NOx from turbine exhaust has been used successfully for at least 12 years. With this process, ammonia (NH3) is mixed with the exhaust gas before it passes through the SCR catalyst where the ammonia reacts selectively with the NOx, producing nitrogen and water. To make this simple reaction work properly over the life of the plant requires attention to issues during design and fabrication of the equipment, operation of the system, and quality control. There are a total of more than 25 issues involved. When all of these issues are recognized and addressed properly, the SCR catalytic system will produce the specified performance for the planned life of the catalyst. This paper identifies, describes, and discusses each of these issues. Most cases of unsatisfactory SCR turbine system performance can be traced to one or more of these issues being overlooked or not addressed properly in the design, construction, or operation of the catalytic system. The purpose of this paper is to make turbine system users aware of what must be done to get the most out of their SCR system.

Modeling of Urea-Water Solution Injection Spray in SCR System

2012 ◽  
Vol 232 ◽  
pp. 583-587
Author(s):  
Nayak S. Nagaraj ◽  
N. Kapilan ◽  
Prabhu S. Sadashiva
Keyword(s):  
Catalytic Reduction ◽  
Water Solution ◽  
Exhaust Gas ◽  
Scr Catalyst ◽  
Exhaust Gas Aftertreatment ◽  
Study Results ◽  
Exhaust Stream ◽  
Experimental Values ◽  
Scr System ◽  
Aftertreatment Systems

To control the emissions from the diesel engines of modern automobiles, it requires the development of adequate and advanced exhaust gas aftertreatment devices. Selective Catalytic Reduction (SCR) is a method that can be used in mobile diesel engine aftertreatment systems to reduce harmful NOx emissions. Due to the toxicity and handling problems of ammonia, currently injection of a liquid Urea-Water Solution (UWS) into the exhaust stream approach is used. The water evaporates and the urea undergoes thermal decomposition producing ammonia that reacts with the NOx in the exhaust gas inside a SCR catalyst to produce nitrogen and water vapor. This work presents the study of UWS injection spray using commercial available CFD code, Fire v8.3. The evaporation of water from a single droplet of UWS is investigated theoretically and droplets are treated with Lagrangian particle tracking. Simulation study at different exhaust gas temperatures and injector locations is carried out and compared with experimental values. Thus, the present study results predict the local distribution and the conversion of the reducing agent.

A Novel MnOx Supported Palygorskite SCR Catalyst for Lower Temperature NO Removal from Flue Gases

2011 ◽  
Vol 356-360 ◽  
pp. 974-979 ◽  
Author(s):  
Xian Long Zhang ◽  
Bo Wen Shi ◽  
Xue Ping Wu ◽  
Wei Ping Jiang ◽  
Bao Jun Yang ◽  
...  
Keyword(s):  
Low Temperature ◽  
Manganese Oxide ◽  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Flue Gases ◽  
Scr Catalyst ◽  
No Removal ◽  
Highly Active ◽  
Lower Temperature ◽  
Scr Of Nox

Palygorskite supported manganese oxide catalysts (MnOx/PG) were prepared for lower temperature selective catalytic reduction (SCR) of NOx by NH3. Catalyst’s SCR activity was estimated at varied temperatures. Catalyst’s properties were characterized by XRD, NH3adsorption and TPD. Results showed that MnOx/PG catalyst was highly active for SCR at low-temperature. It was also found that NH3 was mainly adsorbed on palygorskite in two forms. Weakly adsorbed NH3, which was seldom inhibited by loading of MnOx, but was more favorable to SCR. Whereas strongly adsorbed NH3was more likely to be inhibited by MnOx loading but was inessential for SCR.

Optimized Ammonia Injection for Power Plant SCR Systems

2007 ◽  
Author(s):  
Mark A. Buzanowski ◽  
Dani Fadda
Keyword(s):  
Catalytic Reduction ◽  
Nox Reduction ◽  
Experimental Studies ◽  
Life Time ◽  
Mixing Efficiency ◽  
Exhaust Gas ◽  
System Pressure ◽  
Mixing Distance ◽  
Scr System ◽  
Ammonia Injection

Ammonia injection grid (AIG) is used to introduce vaporized ammonia (NH3) into an exhaust gas stream for nitrous oxide (NOx) reduction in selective catalytic reduction (SCR) systems. Computational and experimental studies on the AIG resulted in significant improvements in the turbulence mixing between the injected ammonia and the exhaust gas. Improved mixing is instrumental to maximize catalyst performance, extend catalyst life time, minimize catalyst volume, decrease system pressure drop, minimize reagent use and ammonia slip, minimize the overall size of the SCR system, and minimize risks associated with designing the SCR system. It is found that an AIG with a turbulence-generating edge dramatically increases the mixing efficiency and, therefore, reduces the mixing distance required to obtain acceptable distributions of the NH3 to NOx ratio. Results indicate over 50% reduction of the required mixing distance due to the turbulence generating edge. This work summarizes the obtained results from computational CFD simulations for two-dimensional and three-dimensional models, however the proposed arrangement of the injection grid has been successfully tested in laboratory experiments and applied to several commercial power generating systems. The commercial performance results will be reported in the subsequent publications.

Development of the New NOx Reduction Catalyst With Hydrocarbons and the Cleanup Systems of Exhaust Gases for Lean-Burn Gas Engines

1999 ◽  
Author(s):  
Yukimaro Murata ◽  
Shigeo Satokawa ◽  
Ken-ichi Yamaseki ◽  
Hiromichi Yamamoto ◽  
Hiroshi Uchida ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Nox Reduction ◽  
Reducing Agent ◽  
Exhaust Gas ◽  
Lean Burn ◽  
Scr Catalyst ◽  
Exhaust Gases ◽  
Scr System ◽  
Three Way Catalyst ◽  
Al2o3 Catalyst

Abstract Development of cleanup technology for combustion waste is more and more necessary today. The emissions of stationary natural-gas-fueled engines can be purified by in-engine methods and by treatment of the exhaust gases. This paper describes the latter technologies. There are two conventional technologies for nitrogen oxides (NOx) reduction methods by the three-way catalyst and the selective catalytic reduction (SCR). The three-way catalyst operates only well within a narrow air-to-fuel ratio window, but when the exhaust gas is too lean, the NOx will not be removed. The SCR of NOx in exhaust gas has the advantage that the engine process itself does not have to be adapted and closely controlled as in case of extended lean-burn technologies. Ammonia or urea injected into the exhaust gas must be used as the reducing agent with conventional SCR system. However, the addition of a SCR system for the small or middle size cogeneration system, it would pose problems regarding cost and space for storage and injection of the reducing agent. Therefore, we have examining the catalyst which is able to reduce NOx with hydrocarbons (HC) containing in exhaust gas itself, and we developed the new HC-SCR catalyst. The de-NOx system using the HC-SCR catalyst has numerous advantages as follows: 1) Compactness and low cost: catalyst unit only 2) High efficiency: adaptation of lean-burn technology for engine operation 3) High performance: excellent catalytic activity and durability 4) Safeties: no use of ammonia as a reducing agent In this study, we report the catalytic activity of the new catalyst and propose a total cleanup system for exhaust gases of lean-burn gas engines. Alumina-supported silver (Ag/Al2O3) was used for the new catalyst. When the measurement was carried out with one reducing gas in the reactant gas each, propane and propane were most effective for NOx reduction, ethane and ethylene were secondly effective for NOx reduction. Practical test of the Ag/Al2O3 catalyst was carried out using a real exhaust gas from a 400 kW class lean-bum gas engine. The full-size catalyst was obtained by washcoating the catalyst powder on a metallic monolithic honeycomb substrate (size: 650 mm ϕ × 324 mmL, 200 cells/inch2). When the engine was operated at 400 kWe output, temperature of the exhaust gas was 762 K and GHSV was 17635 h−1. The NOx conversion was reached to 30% and the catalytic activity was maintained after the operation for more than 2000 hr. Conventional alumina-supported platinum (Pt/Al2O3) catalysts were mounted to exhaust gas line for cleanup test. The emission of CO and aldehydes was in the exhaust gas, but it could be highly removed by the Pt/Al2O3 catalyst. Practical tests of this catalyst were carried out using 300–400 kW class lean-burn gas engines. GHSV of these catalysts were about 50,000 h−1. The CO and aldehydes conversion were reached to more than 90% and the catalytic activities were maintained after the operation for about 10,000 hr.

Catalytic Control of NOx, CO, and NMHC Emissions From Stationary Diesel and Dual-Fuel Engines

1992 ◽  
Vol 114 (3) ◽  
pp. 597-601 ◽  
Author(s):  
R. W. Bittner ◽  
F. W. Aboujaoude
Keyword(s):  
Catalyst Surface ◽  
Catalytic Reduction ◽  
Catalyst System ◽  
Oxidation Catalyst ◽  
Dual Fuel ◽  
Catalyst Structure ◽  
Scr Catalyst ◽  
Heavy Hydrocarbons ◽  
Dual Fuel Engines ◽  
Scr System

Selective Catalytic Reduction (SCR) and oxidation catalyst technology have been applied to a stationary diesel and dual-fuel (natural gas and #2 diesel) engine for catalytic control of nitrogen oxides (NOx), carbon monoxide (CO), and nonmethane hydrocarbon (NMHC) emissions. At rated conditions, NOx emissions have been effectively reduced by up to 90 percent, with little loss of SCR catalyst performance after 850 hours of operation. Using adequate control of the ammonia (NH3) feed, the SCR system was capable of maintaining NH3 slip to 10 ppm or less. CO and NMHC were reduced by 93 and 85 percent, respectively. Little soot was observed on the surface of the catalyst due to the use of a catalyst system that minimizes the buildup of heavy hydrocarbons on the catalyst surface. In addition, the catalyst structure effectively resisted the buildup of sulfur compounds that could cause premature deactivation of the catalyst.

Compound Control Strategy Based on Active Disturbance Rejection for Selected Catalytic Reduction systems

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Jinbiao Ning ◽  
Fengjun Yan
Keyword(s):  
Control Strategy ◽  
Disturbance Rejection ◽  
Catalytic Reduction ◽  
Exhaust Gas ◽  
Gas Temperature ◽  
Model Uncertainties ◽  
Compound Control ◽  
Active Disturbance Rejection ◽  
Exhaust Gas Temperature ◽  
Scr System

Urea-based selected catalytic reduction (SCR) systems are effective ways in diesel engine after-treatment systems to meet increasingly stringent emission regulations. To achieve high NOx reduction efficiency and low NH3 slip, the control of the SCR system becomes more challenging, especially in transient operating conditions with model uncertainties. To effectively address this issue, this paper proposed a compound control strategy with a switching mechanism between an active disturbance rejection (ADR) controller and a zero-input controller. The ADR controller estimates and rejects the total (internal and external) disturbances from the SCR system when the exhaust gas temperature is high and its variation is small. The zero-input controller is used to lower ammonia surface coverage ratio to avoid high ammonia slip when exhaust gas temperature suddenly rises. The proposed control strategy is validated through a high-fidelity GT-Power simulation for a light-duty diesel engine over steady states and federal test procedure (FTP-75) test cycle. Its effectiveness is demonstrated especially in rapidly transient conditions with model uncertainties.

Improvement of Selective Catalytic Reduction System Performance in Combined Cycle Power Plants

2003 ◽  
Author(s):  
Anatoly Sobolevskiy ◽  
Tom Czapleski ◽  
Richard Murray
Keyword(s):  
Selective Catalytic Reduction ◽  
Mass Flow ◽  
System Performance ◽  
Gas Turbines ◽  
Power Plants ◽  
Catalytic Reduction ◽  
Active Material ◽  
Combined Cycle ◽  
Nox Emissions ◽  
Scr System

Environmental regulations are very stringent in the U.S., requiring very low emissions of nitrogen oxides (NOx) from combined cycle power plants. Selective Catalytic Reduction (SCR) systems utilizing vanadium pentoxide (V2O5) as the active material in the catalyst are a proven method of reducing NOx emissions in the exhaust stack of gas turbines with heat recovery steam generators (HRSG) to 2–4 ppmvd. These low NOx emissions levels require an increase of SCR removal efficiency to the level of 90+ % with limited ammonia slip. The distribution of flow velocities, temperature, and NOx mass flow at the inlet of the SCR are critical to minimizing NOx and ammonia (NH3) concentrations in HRSG stack. The short distance between the ammonia injection grid and the catalyst in the HRSG complicates the achievement of homogeneous NH3 and NOx mixture. To better understand the influence of the above factors on overall SCR system performance, field testing of combined cycle power plants with an SCR installed in the HRSG has been conducted. Uniformity of exhaust flow, temperature and NOx emissions upstream and downstream of the SCR were examined and the results served as a basis for SCR system tuning in order to increase its efficiency. NOx mass flow profiles upstream and downstream of the SCR were used to assess ammonia distribution enhancement. Ammonia flow adjustments within a cross section of the exhaust gas duct yielded significantly improved NOx mass flow uniformity after the SCR while reducing ammonia consumption. Based on field experience, a procedure for ammonia distribution grid tuning was developed and recommendations for SCR performance improvement were generated.

Study on Calibration Technique of Commercial Vehicles SCR System Based on MAP Diagram

2012 ◽  
Vol 229-231 ◽  
pp. 2643-2647 ◽  
Author(s):  
Guang Tao Yao ◽  
Cheng Lin Deng ◽  
Xin Yun Zi ◽  
Hai Long Pang ◽  
Zi Rong Guo
Keyword(s):  
Control System ◽  
Catalytic Reduction ◽  
Calibration Method ◽  
Exhaust Gas ◽  
Commercial Vehicles ◽  
Calibration Technique ◽  
Effective Measure ◽  
Emission Regulation ◽  
Spray Control ◽  
Scr System

Selective Catalytic Reduction (SCR) technology is an effective measure to reduce NOxemissions of diesel for commercial vehicles. The purifying effect of Urea-SCR exhaust gas purification device is related to calibration of the parameter of urea control system. Based on MAP diagram , the calibration method of urea spray control system in Urea-SCR system was studied on. Through verifications of ESC and ETC,it is reflected that calibrated MAP diagram can effectively reduce NOxemissions of diesel if used in the control system and emissions could meet the standards of 4th and 5th stage national emission regulation.

scholarly journals Hybrid Technology for DeNOxing by LNT-SCR System for Efficient Diesel Emission Control: Influence of Operation Parameters in H2O + CO2 Atmosphere

Catalysts ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 228
Author(s):  
Marina Cortés-Reyes ◽  
Concepción Herrera ◽  
María Ángeles Larrubia ◽  
Luis J. Alemany
Keyword(s):  
Catalytic Reduction ◽  
Scale Up ◽  
Lean Nox Trap ◽  
Scr Catalyst ◽  
Temperature Range ◽  
Small Pore ◽  
Lean Nox ◽  
Operation Parameters ◽  
The Rich ◽  
Scr System

The behavior and operation parameters were analyzed for the hybrid LNT-SCR (Lean NOx-Trap–Selective Catalytic Reduction) system with advanced catalyst formulations. Pt-Ba-K/Al2O3 was used as an NSR (NOx Storage and Reduction) or LNT catalyst effective in NOx and soot simultaneous removal whereas Cu-SAPO-34 with 2 wt.% of copper inside the structure was the small pore zeolite employed as the SCR catalyst. Under alternating and cyclic wet conditions, feeding volumetric concentrations of 1000 ppm of NO, 3% of O2, 1.5% of water, 0.3% of CO2, and H2 as a reductant, the NOx-conversion values were above 95% and a complete mineralization to nitrogen was registered using θ ≤ 3 (20 s of regeneration) and a hydrogen content between 10,000 and 2000 ppm in the whole temperature range tested. An excess of hydrogen fed (above 1% v/v) during the rich phase is unnecessary. In addition, in the low temperature range below 250 °C, the effect is more noticeable due to the further ammonia production and its possible slip. These results open the way to the scale up of the coupled catalytic technologies for its use in real conditions while controlling the influence of the operation map.

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