【作者】

Kristoffer Sandelin

【摘要】

该论文已在赫尔辛基举行的第28届CIMAC大会上发表，论文的版权归CIMAC所有。Since January this year, new requirements are in place regulating the NOx emissions from ship’s engine exhausts. For decades Selective Catalytic Reduction (SCR) has been an established method for NOx abatement on board seagoing vessels and SCR equipment has been installed on a large number of four-stroke diesel engines. So far, only a few large marine two-stroke diesel engines have been equipped with SCR. The exhaust gas temperatures of such two-stroke diesel engines are in general lower compared to four-stroke engines so, in order to obtain sufficient operating temperatures, the SCR can be placed upstream of the turbine (turbocharger). As a consequence, the catalyst is operating at elevated pressures and high temperatures during high loads of the engine. On the other hand, at part loads the exhaust gas is close to ambient pressure and the temperature is at the lower operating limit of the SCR. In 2015 Winterthur Gas & Diesel conducted a series of tests on a full scale pre-turbocharger SCR to establish engine test-bed procedures, map the performance of the engine/SCR, and to demonstrate compliance with Tier III limits. Moreover, a series of laboratory and bench scale experiments were conducted in order to test the catalyst operation and, explicitly, to be able to assess the effects of temperature and pressure on the catalyst performance. Our tests show that a modern two–stroke engine, in combination with an SCR upstream the turbocharger, presents a fuel-flexible NOx compliant solution for sea-going vessels. This paper confirms methods for predicting the operating temperature of the catalyst when using residual fuels and when operating at elevated as well as atmospheric pressures. We show that the absolute minimum temperature for long-term operation is limited by the condensation of ammonium- and sulphate-containing salts in the bulk phase and that the SCR must not run for long periods at temperatures where significant amounts of the salt can condense in the catalyst pores. In summary, careful control of the exhaust gas temperature of the two-stroke engine enables successful SCR operation with low sulphur fuels as well as with residual fuels containing high amounts of sulphur.

【会议名称】

第28届CIMAC会议

【会议地点】

芬兰 赫尔辛基

【下载次数】

4

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