資料―1

　

INTERNATIONAL MARITIME ORGANIZATION

　

　

　

MARINE ENVIRONMENT PROTECTION

COMMITTEE

49th session

Agenda item 4

　

　

　

　

　

1 It is described in the NOx Technical Code that the deviation of the NOx value from the shop test results at the time of sea trial is 10% and when residual fuel is used the allowance will be 10%, but not more than 15%, in total. However, these figures were not based on the actual monitoring data.

　

2 Until recently, we had no experiences on continuous NOx monitoring under the condition of commercial voyages that use various kinds of residual fuels so far. Therefore, Japan started a three-year on board study of NOx measurement from FY2001 aimed at the following 3 goals:

　

　

　

3 Sample ships were selected to cover every type of engine (MAN-B&W, Wartsila and Mitsubishi) in the market now. And also selected were different type of vessels (VLCC, container and another) and also the routes of vessels were different. One-year measurements for IKOMASAN and NYK ANTARES have been completed and a measurement for ship B is now being carried out. Fuel oil samples were taken from the engine inlet and analyzed by DNVPS. These were then tested by the constant volume combustion chamber testing rig.

　

　

　

4 The summary of the results of the study was reported to the 46^th session of the DE Sub-Committee (DE46/INF.5) and the full version of a progress report is attached as the Annex to this document. Conclusions of the report are as follows:

　

　

　

5 The Committee is invited to take note of this information.

　

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 Regarding the prevention of air pollution from the ship, IMO has adopted the Annex VI of MARPOL 73/78 in 1997. Japan has carried out a continuous NOx monitoring on board test by using 3 ships under the commercial operation condition from FY2001 prior to the start of the regulation to find out practical and useful devices of monitoring. This reports the details of the test to give a future reference of the NOx on board monitoring.

　

　

 As shown in below, at the time of the periodical survey of the IAPP certificate, the NOx monitoring device is prescribed as one of the three measures of the verification procedure of IAPP certificate.

　

 However, so far, we have no experiences of long term continuous NOx monitoring of the propulsion engine, under the condition of commercial voyages that uses various kinds of residual fuels. In NOx technical code, it is described that the deviation of the NOx value from the shop test results at the time of sea trial is 10% and when residual fuel is used allowance will be 10% but not more than 15% in total. But this seems that these figures were not decided based on the concrete data.

　

　

　

　

 The project was carried out as 3 years project from the fiscal year of 2001. We have selected three vessels that have different types of ship type, route of voyage and engine type. It is planned to carry out the continuous NOx monitoring for almost 1 year each. Also, all the fuel oil, which were bunkered in this period, are sampled for component analysis especially for nitrogen content and carried out the combustion test by using constant volume test rig.

　

　

　

 Test vessels were selected to cover every type of engines (MAN-B&W, Wartsila and Mitsubishi) in the market now. And also selected different type of vessels (VLCC, container and PCC) and also route of vessels were different. The test was started from the fiscal year of 2001 using the first and second vessels. From the fiscal year 2002, the third vessel was joined to the project

　

　

5.1 Characteristic of Zirconia (ZrO2) Sensor

　

 Zirconia (ZrO2) sensors are widely used in after-treatment system of exhaust gas using three-way catalyst especially for gasoline engine for automobile, with its quake- and shock-proof ability, and maintenancebility. It is also popular for measurement purposes, for vehicle application, as well as for marine application such as for inert gas leak detector in tanker. Table 5.1.1 shows ZrO2 sensors in various measurement uses.

　

　

5.1.1 Comparison of Sensors for NOx Measurement

　

 Sensors with principles such as ZrO2 method, chemi-luminescence detection (CLD), non-dispersive infrared detection (NDIR), ultraviolet ray detection, and controlled potential electrolysis can measure NOx. The sensors are operated under normal temperature, except for the ZrO2 sensor which is operated under high temperature, and require sampling systems with suction pump or water ejector. Considering the on-board usage, the sensor that has tolerance for vibration and shock at installed position and has maintenancebility is desirable. Table 5.1.1 shows comparison among measurement principles. NDIR and ultraviolet ray sensors which are easily effected by vibration and shock are excluded here.

　

　

 As is shown in the table, ZrO2 sensor has tolerance for vibration and shock at installed position, simple configuration for maintenancebility, and equivalent function and performance to CLD. Thus, one can assume that it is the most suit principle for on-board usage, which has various limitation for gas measurement.

　

 ZrO2 sensor is very useful due to the fact that it is capable of measuring NOx and O2 simultaneously only with a single sensor, which eliminates installing NOx analyzer and O2 analyzer separately on-board.

　

5.1.2 Analyzer Using ZrO2 Sensor and its Principle

　

 Figure 5.1.2.1 shows a ZrO2-type NOx analyzer which is on the market at the moment. In-situ NOx sensor (figure on the upper left) can be attached directly to measuring position so that it requires no gas sampling. The signal is processed and displayed on the receiver (figure on the upper right). Practically, in-situ measurement is possible for automobile where exhaust pipe is comparatively small. Sampling with ejector will be more suitable for ships with large exhaust pipe in order to measure exhaust gas at the center of the pipe.

　

　

　

　

 Next, measurement principles are explained. Gas is measured at the element, 20 mm long and a few mm thick, shown in fig. 5.1.2.1 (lower). Figure 5.1.2.2 is enlarged diagram of the element.