experimental study of selective catalytic reduction ...

Proceedings of ICSEM‘14- 2nd International conference on science, Engineering and management, Srinivasan Engineering college, Tamil Nadu, India, March 28-29,2014 Available @ www.ijaert.org, ISSN No.: 2348 – 8190

EXPERIMENTAL STUDY OF SELECTIVE CATALYTIC REDUCTION SYSTEM ON CI ENGINE FOR REDUCTION OF NOX WITH INJECTION OF AQUEOUS UREA SOLUTION 1

R. Praveen , S. Natarajan 1

2

P.G student, Mechanical Department, Sri Venkateswara College of Engineering, Tamilnadu,India, [email protected] 2

Asst.Professor, Mechanical Department, Sri Venkateswara College of Engineering, Tamilnadu,India, [email protected]

ABSTRACT Nowadays exhaust emission control from internal combustion engines have become one of the most important challenges. Oxides of nitrogen (NOx) are one of the major hazardous pollutants that come out from diesel engines. There are various techniques existing for NOx control but each technique has its own advantages and disadvantages. Technologies available for NOx reductions either increase other polluting gas emission or increase fuel consumption.The objective of this paper is to determine the maximum reductions of NOx emissions by varying concentration of urea solution with reduction catalyst. An aqueous solution of urea was injected in engine exhaust pipe for reducing NOx emissions in single cylinder light duty stationery DI diesel engine. A concentration of urea solution varying from 30 to 35% by weight with constant flow rates and tested with fitting Titanium dioxide (TiO2) coated catalyst which controls by products of ammonia and water vapour. Keywords: Diesel engine emission,SCR, NOxReduction,urea, catalyst – Titanium. 1. INTRODUCTION: The energy requirement has increased exponentially over the past decades due to industrialisation and the changes of subsequent lifestyle. Most of this energy is generated from fossil fuels such as coal, natural gas, gasoline, and diesel. Almost 90% of the present energy source is based on the combustion of fossil fuels and biomass.In last few decades, the environmental effects of pollutant emission from combustion sources have becoming increasingly serious. Diesel engines are widely used in many areas like automobiles, locomotives marine engines power generations etc.., due to its high power output and thermal efficiency. Even though the diesel engines give more benefits, the human discomfort caused by pollutant emission of these engines has to be considered. The major pollutant emissions of the diesel engines are NOx, particulate matters, smoke and soot particles.Although all other emissions, NOx is one of the most important emission from diesel engine. It plays an important role in the atmospheric ozone destruction and global warming. It is also most precursors to the photochemical smog. Component of smog irritate eyes and throat, stir up asthmatic attacks, decrease visibility and damages plants and materials as well. By dissolving with water vapour NOx from acid rain which has direct and indirect effects both on human and plants. There are several techniques for NOx removal. Selective catalytic reduction (SCR) of NOx with urea is considered as promising technology for NOx reduction in diesel engine tail pipe emission.The main requirements for an SCR catalyst of automotive applications are stability over a wide range of temperature (180-600°C).The idea of using urea SCR systems for the reduction of NOx emissions in diesel engines are two decades zold. Since then, many applications have been developed, some of which have reached commercially. But, it is still a challenge for researchers. 1.1 SELECTIVE CATALYTIC REDUCTION (SCR) SCR technology permits the NOx reduction reaction to take place in an oxidising atmosphere. It is called selective because the catalytic reduction of NOx with ammonia(NH 3), urea, monomethylamine, dim ethylamine, try-methylamine, cyanuric acid, carbamates, ammonium carbonate, ammonium bi-carbonate, etc..As a reductant occurs preferentially to oxidation of NH 3 with oxygen with oxides of nitrogen.SCR is a process for reducing the concentration of NOx from the combustion exhaust, which involves the injection of aqueous solution of urea in the tail pipe of a four stroke, constant speed DI diesel engine. Ammonia has been ruled out as a reducing agent, due toxicity and handling issues. So urea has been selected for reductant of choice for most applications, stored on board in an aqueous solution. To overcome the difficulties associated with pure ammonia, urea is selected. Urea can be hydrolysed and decomposed to generate ammonia.An injected aqueous solution of urea solution is decomposed into ammonia and water vapour, and then decomposed ammonia reacts with oxides of nitrogen and reduced into eco-friendly nitrogen and water vapour.

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Proceedings of ICSEM‘14- 2nd International conference on science, Engineering and management, Srinivasan Engineering college, Tamil Nadu, India, March 28-29,2014 (NH2)2CO + 7H2O [(NH2)2CO.7H20] 4NH3 + 4NO + O2

→ → →

[(NH2)2CO.7H2O] HNCO + NH3 + 7H2O 4N2 + 6H2O

[1] [2] [3]

4NH3 + 3O2

→

2N2 + 6H2O

[4]

LITERATURE REVIEW [1]

K. Chithambaramasari (2011) , investigated injection of aqueous solutions of urea in the exhaust for the reduction of NOx was investigated in a single cylinder light duty DI diesel engine. Several kinds of concentration of urea solution varying from 10 to 40% by weight with different flow rates of urea solution varying from 250ml/hr. to 750ml/hr. were tested by fitting vanadium as catalyst which improves the chemical reactions even at a lower temperature of 190°C. By adjusting the 3 way control valve and selecting the needle the flow rate of urea solution should be fixed and maintained constant for a set of experiment. Results show that a maximum of 27.46% of NOx reduction was achieved with an optimised flow rate of 0.75lit/hr. with 10% urea concentration. [2]

S. Ghosh (2013) , investigated injection of aqueous solutions of urea in the tail pipe of a diesel engine for reduction of oxides of nitrogen was carried out in a four stroke, single cylinder, water cooled, constant speed diesel engine. Four observations were made for the exhaust emission NOx analysis of concentration of urea solution 0 to 30% by weight with different flow rates of urea solution as reductant by fitting marine ferromanganese nodule as SCR catalyst. It was observed that 64% of NOx reduction achieved. [4]

S.Ghosh(2013) , Pongamia piñata methylester(PPME) is chosen as alternative fuel for diesel engines. It is renewable and offer potential reduction in CO, HC and smoke emissions due to higher O2 contents in it compared to diesel fuel but higher nitrogen oxides(NOx) emission. Injection of aqueous solutions of urea inthe tail pipe ofa diesel engine fuelled withPongamia piñata methylester (PPME) for the reduction of oxides of nitrogen(NOx) was carried out in a four-stroke, single cylinder, water-cooled, constant speed diesel engine. Four observations were made for various concentration of urea solution 0%, 10%, 20%, and 30% by weight with different flow rates of urea solution as reductant by fitting Marine Ferromanganese nodule as SCR catalyst which improves the chemical reactions. 64% NOx reductionachievedwiththeureaflowrate0.60lit/hr.,30% concentration of urea solution and marine [5] ferro-manganese nodule as SCR.IoannisGekas(2002) , This paper discusses the choice of catalyst types to reduce the NOx emissions down to the EuroV level. A novel Urea injection system is also presented, which is based on a mass produced digital dosing pump that is combined with an electronic control unit specially developed for controlling theUrea-SCR process on-board vehicles. It is shown that it is possible to have a NOx conversion above 80% with ammonia slip below 10ppm using 30 litres of 130 cpsi catalysts for a 12 diesel engine. By increasing the cell density to 300cpsi it is possible to reduce the catalyst volume by 2/3 downto 20 litres for the same engine. 2. EXPERIMENTAL SETUP The experiment was conducted in a light duty stationary single cylinder,four-stroke, air-cooled, direct injection Kirloskar Engine. The schematic diagram of selective catalytic reduction system as shown in the Figure.1 and photographic viewof SCR is shown in Figure1.a.The engine was connected to an electrical dynamometer and CRYPTON 205 five-gas analyser and AVL smoke meter. The torque can be varied from the control panel.

1 2

Air Tank Air Filter

11 12

Battery Relay 761

Proceedings of ICSEM‘14- 2nd International conference on science, Engineering and management, Srinivasan Engineering college, Tamil Nadu, India, March 28-29,2014 3 4 5 6 7 8 9 10

Inlet Valve 13 Engine 14 Electrical Dynamometer15 Loading Device 16 Exhaust Valve 17 Urea Tank 18 Motor 19 Pressure Relief Valve 20

Heater Pressure Gauge Solenoid Valve Mixing Chamber SCR Catalyst CRYPTON 295 Five Gas Analyser AVL Smokemeter Exhaust Gas

Fig. 1.a. Photographic view of SCR 3. METHODOLOGY Before starting the engine, urea solution should be prepared for different concentration varying with 30%, 32.5% and 35% by weight. By adjusting the flow control valve and pre-setting of injection pressure 6bar should be fixed and maintained constant throughout a set of experiment. The heater and solenoid valve is actuated by relay controller through 12V battery. The purpose of heater was evaporation of urea solution and spraying time of urea solution is control by 12V solenoid valve. Initially the engine was started and allowed the engine with constant speed for some period of time. The engine was loaded gradually in the order of 25%, 50%, 75% and 100% of full load. For every loading the emission of HC, CO, CO 2, O2, NOx and smoke density were recorded. Repeated the experiment for different concentration of urea solution with constant flow rate of urea solution. 4. RESULTS AND DISCUSSIONS Fig 2 to 6 indicates variations of various engine emissions with respect to engine load for various concentration of urea solution Figure: 2 shows that variations of NOx emissions with engine load of diesel fuel without urea solution and SCR at constant speed of the engine. From the graph it shows that the NOx emissions increases with the increase of engine load due to high combustion temperature.

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Proceedings of ICSEM‘14- 2nd International conference on science, Engineering and management, Srinivasan Engineering college, Tamil Nadu, India, March 28-29,2014

Oxides of Nitrogen (g/kw-hr)

6 5

4 3 2

Diesel

1 0 0

25

50

75

100

Load % Fig.2 oxides of nitrogen Vs. Engine Load Figure: 3shows that variations of NOx emissions with engine load of diesel fuel with 30% urea solution with SCR at constant speed of the engine. From the graph it shows that the NOx emissions decrease with the injection of 30% urea solution.

Oxides of Nitrogen (g/kW -hr)

6 5 4 3

Diesel

2

30% Urea

1 0 0

25

50

75

100

Load %

Fig.3 oxides of nitrogen Vs. Engine Load (30% urea concentration Figure: 4 shows that variations of NOx emissions with engine load of diesel fuel with 32.5% urea solution with SCR at constant speed of the engine. From the graph it shows that the NOx emissions decrease with the increase of the concentration of urea solution.

763


(g/k W -hr)

6 5 4

Oxides of Nitrogen

3 Diesel 2

32.5% Urea

1 0

0

25

50

75

100

Load % Fig.4 oxides of nitrogen Vs. Engine Load (32.5% urea concentration) Figure: 5 shows that variations of NOx emissions with engine load of diesel fuel with 35% urea solution with SCR at constant speed of the engine. From the graph it shows that the NOx emissions further decreases with the increase of the concentration of urea solution.

of Oxides Nitrogen(g/kW

-hr)

6 5 4 3 2

Diesel

1 0 0

25

50

75

100

Load % Fig.5 oxides of nitrogen Vs. Engine Load (35% urea concentration) Figure: 6 shows that variations of NOx emissions with engine load of diesel fuel with various concentration of urea solution and a constant flow rate 0.75lit/hr. with SCR at constant speed of the engine. From the graph it shows that the NOx emissions decrease drastically by introducing titanium dioxide as SCR in exhaust pipe in engine.

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Oxides of Nitrogen (g/kW -hr)


6 5 4 3 2 1 Load %

0 0

25

50

75

100

Fig.6 oxides of nitrogen Vs. Engine Load (varying urea concentration) 5. CONCLUSION From the study it concluded that urea injection with titanium dioxide as SCR in the exhaust pipe gives a maximum reduction of about 62% NOx emissions during 35% concentration of aqueous urea solution with a constant flow rate of 0.75lt/hr. Thus it indicates that the catalyst used in the test engine commercially effective method method for controlling NOx from Diesel Engines. ACKNOWLEDGEMENTS The encouraging support of brother, laboratory technicians, our Mechanical Head of Department, Supervisor and College Management was gratefully acknowledged. REFERENCES [3] K. Chithambaramasari, N.V. Mahalakshmi and K. Jayachandran, ―Application of SCR technique in NOx reduction of Diesel Engine Emission by Urea Injection Method‖, Canadian Journal on mechanical sciences & Engineering, (December 2011), Vol.2 No.8. [4] S. Ghosh, Dr. S.N. Chaudhuri and D. Dutta, ―Reduction of NOx emission by urea injection and marine ferromanganese nodule as SCR of diesel engine‖, International Journal of Engineering Research & Technology, (January 2013), Vol.2 issue 1. [5] M. Koebel, M. Elsener and M. Kleemann, ―Urea-SCR: a promising technique to reduce NOx emissions from automotive diesel engines‖, Elsevier catalysis today, (2000), Pg. 335-345. [6] S. Ghosh, S.N. Chaudhuri and D. Dutta, ―NOx reduction by using urea injection and marine ferromanganese nodule as SCR of a diesel engine fuelled with pongamia pinnata methyl ester‖, International Journal of Modern Engineering Research, (April 2013), Vol.3 issue 2. Ioannis Gekas, Par Gabrielsson and Keld Johansen, ―Urea-SCR catalyst system selection for fuel and PM optimized engines and a demonstration of a novel urea injection system‖, Society of Automotive Engineers, (2002-01-0289).

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