Highly efficient and economical nitrogen oxides controlled by an in-furnace urea solution pyrolysis coupled with SCR system for a coal-fired utility boiler

2012 ◽  
Vol 8 (4) ◽  
pp. 593-606 ◽  
Author(s):  
Hao Zhou ◽  
Shantao Hu ◽  
Guiyuan Mo ◽  
Qi Tang ◽  
Kefa Cen
Keyword(s):  
Nitrogen Oxides ◽  
Urea Solution ◽  
Utility Boiler ◽  
Highly Efficient ◽  
Scr System

scholarly journals The Development and Implementation of Model-Based Control Algorithm of Urea-SCR Dosing System for Improving De-NOx Performance and Reducing NH3-Slip

2011 ◽  
Author(s):  
Soo-Jin Jeong ◽  
Woo-Seung Kim ◽  
Jung-Kwon Park ◽  
Ho-Kil Lee ◽  
Se-Doo Oh
Keyword(s):  
Control Algorithm ◽  
Catalytic Reduction ◽  
Fluid Model ◽  
Nox Reduction ◽  
Reaction Model ◽  
Urea Solution ◽  
Model Based Control ◽  
Model Based ◽  
Nh3 Emission ◽  
Scr System

The selective catalytic reduction (SCR) system is a highly-effective aftertreatment device for NOx reduction of diesel engines. Generally, the ammonia (NH3) was generated from reaction mechanism of SCR in the SCR system using the liquid urea as the reluctant. Therefore, the precise urea dosing control is a very important key for NOx and NH3 slip reduction in the SCR system. This paper investigated NOx and NH3 emission characteristics of urea-SCR dosing system based on model-based control algorithm in order to reduce NOx. In the map-based control algorithm, target amount of urea solution was determined by mass flow rate of exhaust gas obtained from engine rpm, torque and O2 for feed-back control NOx concentration should be measured by NOx sensor. Moreover, this algorithm cannot estimate NH3 absorbed on the catalyst Hence, the urea injection can be too rich or too lean. In this study, the model-based control algorithm was developed and evaluated based on the analytic model for SCR system. The channel thermo-fluid model coupled with finely tuned chemical reaction model was applied to this control algorithm. The vehicle test was carried out by using map-based and model-based control algorithms in the NEDC mode in order to evaluate the performance of the model based control algorithm.

The Large Capacity Pulverized Coal Fired Utility Boiler and the Low NOx Combustion Technology Developments in China in Response to Environmental Challenges

2011 ◽  
Author(s):  
Hao Zhou ◽  
Guiyuan Mo ◽  
Kefa Cen
Keyword(s):  
High Efficiency ◽  
Catalytic Reduction ◽  
Pulverized Coal ◽  
Large Capacity ◽  
Environmental Challenges ◽  
Utility Boiler ◽  
Integrated Technology ◽  
Combustion Technology ◽  
Low Nox Combustion ◽  
Scr System

Large capacity pulverized coal fired utility boiler technology is in quick developments in China, hundreds of super critical boilers have been constructed in the last several years which can achieve high efficiency and low pollutants emissions. The different types of super critical boilers are introduced in this paper, they include the single-furnace with double fireball corner fired furnace, the wall fired furnace and the tower-type furnace. The low NOx combustion technologies have been widely used to face the environmental challenges. The low NOx technologies employed in pulverized-coal boilers consist of the combustion modification and post-combustion technology. The low NOx combustion modification technology includes the low NOx burner, close coupled over fire air (CCOFA) and separated over fire air (SOFA). The post-combustion technology consists of selective non-catalytic reduction (SNCR) and selective catalytic reduction (SCR) technologies. Zhejiang University develops integrated low NOx technology, including the low NOx combustion system, SNCR system and SCR system. This integrated technology can reduce the NOx emissions to be lower than 50 mg/Nm3.

scholarly journals The issue of improving the efficiency of nitrogen oxide neutralization systems in diesel internal combustion engines

2021 ◽  
Vol 1 (2) ◽  
pp. 101-112
Author(s):  
A.V. Shabanov ◽  
◽  
D.V. Kondratiev ◽  
V.K. Vanin ◽  
A.Yu. Dunin ◽  
...  
Keyword(s):  
Nitrogen Oxides ◽  
Internal Combustion Engine ◽  
Power Plants ◽  
Internal Combustion Engines ◽  
High Efficiency ◽  
Combustion Engine ◽  
Thermal Power ◽  
Internal Combustion ◽  
Urea Solution ◽  
Exhaust Gas

The most effective method of reducing nitrogen oxides in diesel exhaust gas is selective purifica-tion by the SCR-NH3 method. The method uses ammonia released during thermolysis and hydroly-sis of a urea solution when it is injected through a nozzle into a neutralizer. This method has a rela-tively low efficiency of cleaning the exhaust gas from nitrogen oxides. The main factor hindering the achievement of high efficiency of the NOx neutralization system is the insufficiently high tem-perature during the implementation of this process. The article analyzes various ways to increase the efficiency of the neutralization process and proposes a new method for neutralizing NOx by using urea injection into the cylinders of the inter-nal combustion engine at the expansion stroke in a diesel internal combustion engine. Efficiency can be achieved due to a higher exhaust gas temperature in the cylinder of the internal combustion engine and an increase in the time of the process of thermolysis and hydrolysis of urea. The kinetics of the decomposition of nitrogen oxides, the process of NH3 oxidation, and the cal-culation of temperature conditions in the cylinder of a diesel internal combustion engine at the ex-haust cycle are considered. The experience of neutralization of NOx contained in the flue gases of thermal power plants, where NOx purification takes place at high temperatures without the use of a catalyst, is analyzed. It is shown that the modernization of the SCR-NH3 process, due to the injection of urea at the exhaust stroke in a diesel internal combustion engine, will simplify the existing method of NOx neutralization and at the same time obtain additional advantages for a modern high-speed engine

Modeling and simulation of marine SCR system based on Modelica

2022 ◽  
pp. 146808742110722
Author(s):  
Jie Shi ◽  
Yuanqing Zhu ◽  
Hui Peng ◽  
Haoyu Yan ◽  
Tinghui Li ◽  
...  
Keyword(s):  
Flow Rate ◽  
Great Influence ◽  
Slip Rate ◽  
Urea Solution ◽  
Bench Test ◽  
Stoichiometric Ratio ◽  
Exhaust Gas ◽  
Gas Temperature ◽  
Exhaust Gas Temperature ◽  
Scr System

With the increasing awareness of global marine environmental protection, the emission of ship exhaust pollutants is strictly restricted. Selective catalytic reduction (SCR) technology is the mainstream technology to reduce ship NOx emission and make it meet IMO tier III regulations. A SCR reaction kinetic model based on Modelica language was established by Dymola software to predict the denitration efficiency, ammonia slip rate, and other parameters of SCR system. According to the functional structure of marine SCR system, the SCR system model is divided into urea injection module, mixer module, and SCR reactor module. The model was verified by SCR system bench test of WD10 diesel engine, which proved that the model can preferably reflect the actual situation. Using the established model, the effects of temperature, flow rate, NH3/NOx Stoichiometric Ratio (NSR), and cell density on the denitration performance of SCR system were analyzed. The results showed that the exhaust gas temperature and NSR have a great influence on the denitration efficiency. The injection amount of urea solution in marine SCR system should be based on the exhaust gas temperature and exhaust flow rate.

Highly efficient reversible adsorption of NO2 in imidazole sulfonate room temperature ionic liquids

RSC Advances ◽  
2014 ◽  
Vol 4 (74) ◽  
pp. 39572-39575 ◽  
Author(s):  
Gang Yuan ◽  
Feng Zhang ◽  
Jiao Geng ◽  
You-Ting Wu
Keyword(s):  
Ionic Liquids ◽  
Nitrogen Oxides ◽  
Molecular Imprinting ◽  
Room Temperature ◽  
Room Temperature Ionic Liquids ◽  
Reversible Adsorption ◽  
Highly Efficient ◽  
Wasted Energy

The molecular-imprinting like highly efficient reversible absorption of NO2 in the imidazole sulfonate room-temperature ionic liquids was found, which opens a new way to clean the polluted air and re-utilize the wasted energy in nitrogen oxides.

Simulation and Optimization of Urea-SCR System in Diesel Engine

2013 ◽  
Vol 316-317 ◽  
pp. 1156-1161 ◽  
Author(s):  
Qian Wang ◽  
Duo Zhang ◽  
Jing Wang ◽  
Shuo Li
Keyword(s):  
Chemical Reaction ◽  
Catalytic Converter ◽  
Three Dimensional ◽  
Catalyst System ◽  
Spray Angle ◽  
Urea Solution ◽  
Scr Catalyst ◽  
Simulation And Optimization ◽  
Scr System ◽  
Reaction Characteristic

A three-dimensional Urea-SCR catalytic converter model was simulated with the method of CFD coupled with chemical reaction dynamic in this paper. With the modeling of urea solution injection and spray, the urea spray angle was optimized to reduce the urea wallfilm on the pipe wall. The flow fields and component distributions of a full scale Urea-SCR catalyst system were obtained to analyze the flow and chemical reaction characteristic of SCR system. Finally, an SCR system with a simple blade SCR mixer was simulated, the results indicated that the mixer can accelerate the evaporation and thermolysis of urea solution, and improve reductant uniformity and NOx conversion efficiency of Urea-SCR system.

scholarly journals Analysis of an automotive thermoelectric generator coupled to an electric exhaust heater to reduce NOx emissions in a Diesel-powered Euro VI Heavy Duty vehicle

2021 ◽  
Vol 19 ◽  
pp. 407-412
Author(s):  
A. Massaguer ◽  
◽  
E. Massaguer ◽  
J. Ximinis ◽  
T. Pujol ◽  
...  
Keyword(s):  
Thermoelectric Generator ◽  
Electrical Energy ◽  
Urea Solution ◽  
Nox Emissions ◽  
Exhaust Gas ◽  
Heavy Duty ◽  
New Approach ◽  
Heavy Duty Vehicle ◽  
Automotive Thermoelectric Generator ◽  
Scr System

This study presents a new approach to minimize the amount of NOx emitted by diesel engines of Heavy-Duty Vehicles during low engine regimes and low gases temperature conditions. We propose the addition of an electric Exhaust Gas Heater (EGH) to make the SCR system inject the urea solution at low engine regimes. The second part of this study focuses on the viability to use an Automotive Thermoelectric Generator (ATEG) to generate the energy required by the EGH and thus avoiding the need to consume electrical energy from the vehicle’s system. This EGHATEG system is designed to be energetically closed, so there is no extra consumption of fuel. Experimental results show that NOx emissions reduce up to 80% when an EGH is added to a standard diesel-powered Euro VI Heavy Duty truck configuration. Simulations show that an ATEG installed downstream of the aftertreatment system can produce the energy required by the EGH. This system can improve SCR efficiency up to 55% during low engine regimes.

Selective Catalytic Reduction (SCR) System Installation and Commissioning at the Chow II Power Plant in Chowchilla, California

2003 ◽  
Author(s):  
Don Newburry ◽  
Pat Runnels ◽  
Mike Owings
Keyword(s):  
Power Plant ◽  
Natural Gas ◽  
Selective Catalytic Reduction ◽  
High Efficiency ◽  
Catalytic Reduction ◽  
Industrial Applications ◽  
Urea Solution ◽  
Lean Burn ◽  
High Oxygen Content ◽  
Scr System

Lean burn, natural gas, reciprocating engines are becoming widely utilized for stationary industrial applications due to their high efficiency and low emissions. However, despite the low engine emissions, some locations still require exhaust after-treatment to meet the local emissions requirements. Due to the high oxygen content (greater than 4%) in the exhaust of lean burn engines, 3-Way (non-selective) catalysts are not suitable to reduce NOx. Selective catalytic reduction (SCR), which utilizes a consumable reductant to reduce NOx over a catalyst, is very effective at reducing NOx and is becoming an accepted technology for large, stationary engine applications. In the summer of 2001, Stewart & Stevenson installed 16 Deutz TGB632V16 natural gas fired engines for NEO Corporation at the Chow II power plant. MIRATECH SCR provided and commissioned 16 selective catalytic reduction systems for these engines using a 40% urea solution as the reductant. This paper describes the installed SCR systems and reports some of the emissions testing results and costs. With the SCR systems in place, the engines were successfully able to meet the permitted exhaust emissions requirements of 0.07 g/bhp-hr of NOx, 0.1 g/bhp-hr of CO, and 0.15 g/bhp-hr of VOC’s (volatile organic compounds) with less than 10 ppmvd of ammonia slip @ 15% O2. Additional measurements were made of formaldehyde and acrolein. Very low levels of these emissions were found after the SCR.

Comparison of Lab Versus Engine Tests In the Development of a Highly Efficient Ammonia Formation Catalyst for a Passive SCR System

2015 ◽  
Author(s):  
Gerben Doornbos ◽  
Emma Adams ◽  
Per-Anders Carlsson ◽  
Daniel Dahl ◽  
Mats Laurell ◽  
...  
Keyword(s):  
Highly Efficient ◽  
Scr System ◽  
Ammonia Formation ◽  
Passive Scr ◽  
Versus Engine
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