Resolution MEPC.103(49)

GUIDELINES FOR ON-BOARD NO_X VERIFICATION PROCEDURE - DIRECT MEASUREMENT AND MONITORING METHOD

(Adopted on 18 July 2003)

 

 

THE MARINE ENVIRONMENT PROTECTION COMMITTEE,

 

RECALLING Article 38(a) of the Convention on the International Maritime Organization concerning the functions of the Marine Environment Protection Committee (the Committee) conferred upon it by international conventions for the prevention and control of marine pollution,

 

RECALLING ALSO that the Conference of Parties to the International Convention for the Prevention of Pollution from Ships, 1973, as modified by the Protocol of 1978 relating thereto (MARPOL 73/78), held in September 1997, adopted the Protocol of 1997 to amend MARPOL 73/78 with a new Annex VI on the Prevention of Air Pollution from Ships,

 

NOTING that the 1997 Conference by resolution 2 adopted the Technical Code on Control of Emission of Nitrogen Oxides (NO_x) from Marine Diesel Engines, which in paragraph 2.4.5 provides the option that on-board NO_x verification procedures may be based on a NO_x monitoring and recording device, approved by the Administration, based on Guidelines to be developed by the Organization,

 

BEING AWARE that this requirement cannot be enforced before the entry into force of the Protocol of 1997,

 

BEING AWARE ALSO of the need to develop relevant Guidelines before the entry into force of the Protocol of 1997 in preparation for the implementation of Annex VI of MARPOL 73/78,

 

HAVING CONSIDERED the recommendation made by the Sub-Committee on Ship Design and Equipment at its forty-sixth session,

 

1. ADOPTS the Guidelines for on-board NO_x verification procedure - Direct measurement and monitoring method, as set out in the Annex to this resolution;

 

2. INVITES Governments to apply the Guidelines from the date of entry into force of the Protocol of 1997.

 

Annex.

GUIDELINES FOR ON-BOARD NO_x VERIFICATION PROCEDURE - DIRECT MEASUREMENT AND MONITORING METHOD

 

SAFETY NOTE

 

Due attention is to be given to the safety implications related to the handling and proximity of exhaust gases, the measurement equipment and the storage and use of cylindered pure and calibration gases. Sampling positions and access staging should be such that this monitoring may be performed safely and will not interfere with the engine.

 

PRINCIPLES

 

These Guidelines are intended as an objective, performance-based document. These Guidelines are recommendatory in nature. However, national administrations are invited to base their implementation on these Guidelines. Because the direct measurement and monitoring method is one of the three permissible on-board NO_x verification procedures in the NO_x Technical Code (cf. NO_x Technical Code, paragraph 2.4.4), its accuracy should be comparable to the other methods. Therefore, these Guidelines for approving on-board NO_x monitoring and recording devices appropriately refer to the NO_x Technical Code. References to the NO_x Technical Code emphasize that relevant requirements are already regulated in a mandatory document, even though they are not grouped in a common chapter (e.g. "Direct measurement and monitoring method"). The values determined by this method may not be directly comparable with the test bed results. Of overriding importance for approval is the suitability of the NO_x monitoring and recording devices for on-board use.

 

As a general principle, an on-board NO_x verification procedure should readily facilitate demonstration of compliance with regulation 13 of Annex VI of MARPOL 73/78 (Annex VI). At the same time, it should not be so burdensome as to unduly delay the ship or to require in-depth knowledge of the characteristics of a particular engine or specialist measuring devices not available on board.

 

1. ANALYSING EQUIPMENT

 

1.1 Emission species measurement

 

1.1.1 On-board NO_x monitoring includes, as an absolute minimum, the measurement of gaseous emission concentrations of NO_x (as NO + NO₂).

 

1.1.2 If determination of exhaust flow is performed, utilizing the NO_x Technical Code, appendix 6 (Method 2, universal, carbon/oxygen-balance), then O₂ and/or CO₂ should be measured and provisions in appendix 6 that assume complete combustion may be used in all cases. If the provisions in appendix 6 that do not assume complete combustion are preferred, then additionally CO and HC should be measured.

 

1.1.3 The exhaust gases should be analysed with the following instruments. For non-linear analysers, the use of linearizing circuits is permitted. Other systems or analysers may be accepted, subject to the approval of the Administration, provided they yield equivalent results to that of the equipment referenced below:

 

.1 Oxides of nitrogen (NO_x) analysis

 

The oxides of nitrogen analyser should be of the Chemiluminescent Detector (CLD) or Heated Chemiluminescent Detector (HCLD) type. The exhaust gas sampled for NO_x measurement should be maintained above its dewpoint temperature until it has passed through an NO₂ to NO converter.

 

Note:

 

In the case of raw exhaust gas this temperature should be greater than 333 K (60°C) if the engine is fueled with ISO 8217 DM-grade type fuel and greater than 413 K (140°C) if fueled with ISO 8217 RM-grade type fuel.

 

.2 Carbon dioxide (CO₂) analysis

 

When needed, the carbon dioxide analyser should be of the Non-Dispersive Infrared (NDIR) absorption type.

 

.3 Oxygen (O₂) analysis

 

When needed, the oxygen analyser should be of the Paramagnetic Detector (PMD), Zirconium Dioxide (ZRDO) or Electrochemical Sensor (ECS) type.

 

.4 Carbon mo NO_x ide (CO) analysis

 

When needed, the carbon mo NO_x ide analyser should be of the Non-Dispersive Infrared (NDIR) absorption type.

 

.5 Hydrocarbon (HC) analysis

 

When needed, the hydrocarbon analyser should be of the Heated Flame Ionization Detector (HFID) type. The exhaust gas sampled for HC measurement should be maintained at 463 K ±10 K (190°C ±10°C) from the sample point to the detector.

 

1.2 Analyser specifications

 

1.2.1 The analyser specifications should be consistent with the NO_x Technical Code, appendix 3, paragraphs 1.4, 1.5, 1.6, 1.7, 1.8 and 1.9.

 

1.2.2 The analyser range should be such that the measured emission value is within 15%-100% of the range used.

 

1.2.3 The analysing equipment should be installed and maintained in accordance with manufacturer's recommendations such that the requirements of the NO_x Technical Code, appendix 3, paragraphs 1.5, 1.6, 1.7, 1.8, 1.9 and appendix 4, paragraphs 7 and 8, are met.

 

1.3 Pure and calibration gases

 

1.3.1 Pure and calibration gases, as required, should comply with the NO_x Technical Code, appendix 4, paragraphs 2.1 and 2.2. Declared concentrations should be traceable to national and/or international standards. Calibration gases should be in accordance with the analysing equipment manufacturer's recommendations.

 

1.3.2 Analyser span gases should be between 80%-100% of the analyser scale being spanned.

 

Note:

 

Under certain conditions, only a span gas for the NO_x analyser could be necessary for calibration of the analytical instruments. A NO span gas for a NO_x analyser can be applied as a zero gas for an O₂ or CO₂ analyser if that span gas is balanced only with nitrogen. Ambient air may be applied both as a span gas for an O₂ analyser (i.e. 20.9% O₂) and as a zero gas for a NO_x analyser, provided that the ambient air is uncontaminated by exhaust gas.

 

1.4 Gas sampling and transfer system

 

1.4.1 The exhaust gas sample should be representative of the average exhaust emission from all the engine's cylinders. The gas sampling system should comply with the NO_x Technical Code, paragraph 5.9.3.

 

1.4.2 The exhaust gas sample should be drawn from a zone anywhere between 10%-90% of the duct diameter.

 

1.4.3 In order to facilitate the installation of the sampling probe, an example of a sample point connection flange is given in appendix 1.

 

1.4.4 The exhaust gas sample for NO_x measurement should be maintained so as to prevent NO₂ loss via water or acid condensation in accordance with analysing equipment manufacturer's recommendations.

 

1.4.5 The gas sample should not be dried by chemical driers.

 

1.4.6 The gas sampling system should be capable of being verified to be free of ingress leakage in accordance with analysing equipment manufacturer's recommendations.

 

1.4.7 An additional sample point adjacent to that used should be provided to facilitate quality control checks on the system.

 

2. ENGINE PERFORMANCE AND AMBIENT CONDITION MEASUREMENT

 

2.1 Engine performance measurements

 

2.1.1 Table 1 lists the engine performance parameters that should be measured, or calculated, and recorded at each mode point during on-board NO_x monitoring.

 

Table 1

 

 

2.1.2 Other engine settings necessary to define engine-operating conditions, e.g. wastegate, charge air bypass, turbocharger status, should be determined and recorded.

 

2.1.3 The settings and operating conditions of NO_x control devices should be determined and recorded.

 

2.1.4 The engine power and speed should be measured to determine whether the engine is operated in a mode according to the specified test cycles (cf. section 3.1 of these Guidelines).

 

2.1.5 If it is difficult to measure power directly, uncorrected brake power may be estimated by any other means as approved by the Administration (cf. NO_x Technical Code, paragraphs 6.3.1.3, 6.3.3.2 and 6.3.7). Possible methods to determine brake power include, but are not limited to:

 

.1 indirect measurement as per NO_x Technical Code, paragraph 6.3.3.1; or by

 

.2 estimation from nomographs.

 

2.1.6 The fuel flow (actual consumption rate) should be determined by:

 

.1 direct measurement; or by

 

.2 test bed data as per NO_x Technical Code, paragraph 6.3.1.4.

 

2.2 Ambient condition measurements

 

2.2.1 Table 2 lists the ambient condition parameters that should be measured, or calculated, and recorded at each mode point during on-board NO_x monitoring.

 

Table 2

 

 

2.3 Engine performance and ambient condition monitoring equipment

 

The engine performance and ambient condition monitoring equipment should be installed and maintained in accordance with manufacturers' recommendations such that requirements of the NO_x Technical Code, appendix 4, paragraph 1.3.2 and tables 3 and 4, are met in respect of the permissible deviations.

 

2.4 Electrical equipment: materials and design

 

2.4.1 Electrical equipment should be constructed of durable, flame-retardant, moisture resistant materials, which are not subject to deterioration in the installed environment and at the temperatures to which the equipment is likely to be exposed.

 

2.4.2 Electrical equipment should be designed such that current carrying parts with potential to earth are protected against accidental contact.

 

3. EXHAUST EMISSION MEASUREMENT

 

3.1 Test cycles

 

3.1.1 Engine operation on board under a specified test cycle may not always be possible, but the test procedure, as approved by the Administration, should be as close as possible to the procedure defined in the NO_x Technical Code, paragraph 3.2.

 

3.1.2 Regarding the E3 test cycle, if the actual propeller curve differs from the E3 curve, the load point used should be set using the engine speed, or the corresponding mean effective pressure (MEP) or mean indicated pressure (MIP), given for the relevant mode of that cycle.

 

3.1.3 If the number of measuring points on-board is different from those on the test bed, the number of measurement points and the weighting factors should be approved by the Administration.

 

3.1.4 Regarding the E2/E3/D2 test cycles, a minimum of load points should be used of which the combined nominal weighing factor, as given in the NO_x Technical Code, paragraph 3.2, is greater than 0.50.

 

3.1.5 Regarding the C1 test cycle, a minimum number of one load point should be used from each of the rated, intermediate and idle speed sections.

 

3.1.6 If the number of measuring points on board is different from those on the test bed, the nominal weighting factors at each load point should be increased proportionally in order to sum to unity (1.0).

 

3.1.7 An example of the selection of load points and revised weighting factors are given in appendix 2.

 

3.1.8 The actual load points used to demonstrate compliance should be within ±5% of the rated power at the modal point except in the case of 100% load where the range should be +0 to –10%. For example, at the 75% load point the acceptable range should be 70% - 80% of rated power.

 

3.1.9 At each selected load point, except idle, and after the initial transition period (if applicable), the engine power should be maintained at the load set point within a 5% coefficient of variance (%C.O.V.) over a 10-minute interval. A worked example of the coefficient of variance calculation is given in appendix 3.

 

3.1.10 Regarding the C1 test cycle, the idle speed tolerance should be declared, subject to the approval of the Administration.

 

3.2 Test condition parameter

 

The test condition parameter specified in the NO_x Technical Code, paragraph 5.2.1, should not apply to on-board NO_x monitoring. Data under any prevailing ambient condition should be acceptable.

 

3.3 Analyser in-service performance

 

3.3.1 Analysing equipment should be operated in accordance with manufacturer's recommendations.

 

3.3.2 Prior to measurement, zero and span values should be checked and the analyser should be adjusted as necessary.

 

3.3.3 After measurement, analyser zero and span values should be verified as being within that permitted in the NO_x Technical Code, paragraph 5.9.9.

 

3.4 Data for emission calculation

 

3.4.1 The output of the analysers should be recorded both during the test and during all response checks (zero and span). This data should be recorded on a strip chart recorder or other types of data recording devices.

 

3.4.2 For the evaluation of the gaseous emissions, a 1-Hertz minimum chart reading of a stable 10-minute sampling interval of each load point should be averaged. The average concentrations (conc) of NO_x, O₂ and/or CO₂, if required, and optionally CO and HC, should be determined from the averaged chart readings and the corresponding calibration data.

 

3.4.3 As a minimum, emission concentrations, engine performance and ambient condition data should be recorded over the aforementioned 10-minute period.

 

4. DATA EVALUATION

 

4.1 Fuel composition

 

Fuel composition, to calculate gas mass flow wet (GEXHW), should be provided by one of the following:

 

.1 fuel composition by analysis (carbon, hydrogen and sulphur); or

 

.2 default values, see table 3.

 

Table 3

 

4.2 Exhaust gas density

 

Exhaust gas density, to calculate gas mass flow wet (GEXHW) and NO_x Technical Code Table 5, coefficient "u", should be provided by one of the following:

 

.1 calculation as per the NO_x Technical Code, appendix 6; or

 

.2 default value of 1.293 kg/m³ ( 273.15 K and 101.3 kPa).

 

4.3 Dry/wet correction

 

If not already measured on a wet basis, the gaseous emissions concentrations as per paragraph 2 of these Guidelines should be converted to a wet basis according to:

 

.1 direct measurement of the water component; or

 

.2 calculated in accordance with the NO_x Technical Code, paragraph 5.12.2. (NO_x Technical Code, equation 11, CO may be set to zero).

 

4.4 NO_x corrections for humidity and temperature

 

NO_x corrections for humidity and temperature should be performed as per NO_x Technical Code, paragraph 5.12.3. The reference charge, or scavenge, air temperature (T_{sc ref} ) should be stated and approved by the Administration. The T_{sc ref} values are to be referenced to 25°C sea water temperature and in the application of the T_{sc ref} value due allowance should be made for the actual sea water temperature.

 

4.5 Exhaust gas flow rate

 

Exhaust gas flow rate should be determined by:

 

.1 NO_x Technical Code, paragraphs 5.5.1 or 5.5.2; or

 

.2 NO_x Technical Code, appendix 6, method 2, with not measured species set to zero and CO2AIR, if applicable, set to 350 ppm.

 

4.6 Calculation of emission flow rates and specific emissions

 

The calculation of emission flow rates and specific emissions should be performed as per NO_x Technical Code, paragraphs 5.12.4 and 5.12.5.

 

5. COMPLIANCE REQUIREMENTS

 

5.1 Limit value and allowances

 

The emission value obtained by the direct monitoring and measurement method should be compared to the NO_x emission limit value as given in regulation 13 of Annex VI, plus allowance values as given in the NO_x Technical Code, paragraphs 6.3.11.1, 6.3.11.2 and 6.3.11.3 in order to verify that an engine continues to comply with the requirements of regulation 13 of Annex VI.