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Research Papers: Internal Combustion Engines

Modeling Approach for a Hydrolysis Reactor for the Ammonia Production in Maritime Selective Catalytic Reduction Applications

[+] Author and Article Information
Katrin Johe

Chair of Thermodynamics,
Department of Mechanical Engineering,
Technical University Munich,
Munich 85748, Germany
e-mail: katrin.johe@gmail.com

Thomas Sattelmayer

Chair of Thermodynamics,
Department of Mechanical Engineering,
Technical University Munich,
Munich 85748, Germany
e-mail: sattelmayer@td.mw.tum.de

Contributed by the IC Engine Division of ASME for publication in the JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER. Manuscript received February 20, 2018; final manuscript received February 27, 2018; published online May 24, 2018. Editor: David Wisler.

J. Eng. Gas Turbines Power 140(9), 092802 (May 24, 2018) (8 pages) Paper No: GTP-18-1083; doi: 10.1115/1.4039762 History: Received February 20, 2018; Revised February 27, 2018

The catalytic generation of ammonia from a liquid urea solution is a critical process determining the performance of selective catalytic reduction (SCR) systems. Solid deposits on the catalyst surface from the decomposition of urea have to be avoided, as this leads to reduced system performance or even failure. At present, reactor design is often empirical, which poses a risk for costly iterations due to insufficient system performance. The presented research project proposed a performance prediction and modeling approach for SCR hydrolysis reactors generating ammonia from urea. Different configurations of hydrolysis reactors were investigated experimentally. Ammonia concentration measurements provided information about parameters influencing the decomposition of urea and the system performance. The evaporation of urea between injection and interaction with the catalyst was identified as the critical process driving the susceptibility to deposit formation. The spray of urea solution was characterized in terms of velocity distribution by means of particle-image velocimetry. Results were compared with theoretical predictions and calculation options for processes in the reactor were determined. Numerical simulation was used as an additional design and optimization tool of the proposed model. The modeling approach is presented by a step-by-step method, which takes into account design constraints and operating conditions for hydrolysis reactors.

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Figures

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Fig. 1

Test rig for hydrolysis reactors: cold air from the Roots blower is heated by the two heaters, passes the hydrolysis reactor and the ammonia slip catalyst, before exiting the setup

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Fig. 2

Comparison of the UDR and the HEL for test cases TC1–TC4 and RC

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Fig. 3

Left side: droplet size distributions for Schlick 940 and MAN injector at different distances. Right side: mass reduction for all operation points (droplet diameter 70 μm).

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Fig. 4

Left side: calculated temperature profiles at the catalyst inlet for all operation points (OP1 calc till OP4 calc) by model 1 (Eq. (15)) in comparison with measured temperatures forOP1 (black circles) and OP2 (grey circles). Right side: calculated diffusion length profiles of HNCO at the catalyst inlet for all operation points (OP1 HNCO till OP4 HNCO) with temperature profiles.

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Fig. 5

Temperature profiles for Sim1 (solid line), Sim2 (dashed dotted line) with remaining liquid mass and Sim1 evap (dashed line), Sim2 evap (dashed double dotted line) incorporating the evaporation of the remaining liquid in comparison with temperature measurement points (all at CS4)

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Fig. 6

Procedure of the hydrolysis reactor design method

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