3/2014, In English, Tutkimus ja innovaatiot

Overlook to onboard emission measurements

Introduction

The emission measurement laboratory of Kymenlaakso University of Applied Sciences has a track record of shipping related emission measurements for over twenty years. The laboratory has gathered a lot of onboard experience during this period. This article summarizes some of the practical challenges discovered in course of planning and following through the onboard measurement campaign.

Background

The organization behind the laboratory is Kymenlaakso University of Applied Sciences [referred later as Kyamk]. Kyamk is a university with higher education in both of maritime operations and energy technology. This background produces the innate call for emission control research and development. The fields of development and research include i.e. environmentally friendly energy production and emission control technology.

The emission measurement laboratory of Kymenlaakso University of Applied Sciences was grounded in year 1992. The emission measurement laboratory serves as reliable source of measured data for the needs of various research programmes. The laboratory performs emission measurements in land based power plants and on board ships.

Most of the workload of the laboratory is commissioned by commercial customers; however the participation in research activities is ubiquitous and a vital part of the operation. The laboratory has taken part in several considerable international projects and has completed measurements in well over one hundred vessels with a total of hundreds of engines. The emission measurement laboratory is accredited by FINAS according the SFS-EN ISO/IEC 17025:2005 standard.

Previous project measurement experiences

The Kyamk emission measurement laboratory has taken part in several international projects within last two decades. There are several international projects worth mentioning amongst many: the Mobile project and the recent Snoop and BSR Innoship projects. The Mobile project was managed and conducted by VTT, the Finnish state research organization. The Mobile project included 58 measured engines over time span of several years and it was considered very successful. The Mobile project had a considerable impact of environmental research and legislation in Finland. The Snoop project focused on the ship emissions within Baltic Sea area and it was managed by Finnish Meteorological Institute. The follow-up of the snoop project, BSR Innoship was finished September 2013. An extensive campaign of nine measured ships was conducted in BSR Innoship-project.

Specialized to the practical element

The role of the Kyamk emission measurement laboratory in large research projects has been focused on the practical side of the work, which is conducting the measurements and reporting the results. The laboratory usually does not make scientific conclusions or any deep analysis of the findings. This spawns from the usual organization of the large projects as project groups normally include several fundamental scientific organizations for both basic and advanced research. These organizations do not usually have suitable field equipment or trained personnel for working in the ship environment. This is the niche for Kyamk, as the ability for perform in field operations is the main strength of Kyamk emission measurement laboratory. The diversity of usual project organization results to the current arrangement, which has been a successful and functional division of the labor between practical measurements and scientifically oriented studies.

Agreement with the shipping company

The attitude for emission research of shipping companies can vary a lot. Some companies can be very helpful and even eager to participate, and usually this is the case. In some occasions, however, there is a certain resistance for setting up and conducting the measurements. This is understandable. The measurement crew and the measurement procedure tie up operation personnel which already have a heavy workload. Measurements can also require the specific engines to run at specific loads, or the measurement can require modifications in the running modes of auxiliary equipment (a common example of the latter are the catalyst reactors or water injection systems).

Keeping in mind the need for intense shipping company co-operation the planning of a single measurement run must be started at very early stage. The initial contacts are often taken weeks or even months ahead of the planned measurement run.

One of the basic design elements is the route of the ship. The schedule or the port stop times are often not suitable for the measurement job, and the travel time of the ship sets some limits too. The measurement equipment does not fit for air transport, and this can also limit the measurement window.

The measurement details are usually agreed after the general permission to conduct the measurements is reached. The detailed plan and actions for the ship in question are usually communicated with the onboard crew of the ship. The ship’s engineer always has the final word for the operation. The course of measurement procedure is usually familiar to the technical crew of the ship. Most of the cases there is no need for any special arrangements after the access for the measurement crew is granted. The measurement crew needs to access the engineering section and the chimney premises of the ship, which are normally quite restricted areas.

Measurement process onboard

This chapter describes the generalized set-up of the measurement. The actual measurement procedure follows the appropriate standards and it is not presented here.

The conditions within the ship depend greatly of the type and age of the ship. A brad new car ferry usually does have very different environment than a two decade old bulk carrier. Some details however remain the same: the field measurement work is heavy work, and the passage ways, corridors and ladders are narrow and the exhaust system is hot.

The measurements must be conducted with accuracy and the results must be reliable despite of the environment. This imposes of course some challenges, especially if the surroundings and conditions of the measurement are particularly hard.

Measurement equipment station

The amount of equipment can be quite a lot and the equipment station needs a considerable amount of space. The combination of measurement equipment depends of the measurement details. For example, if there is a need to make simultaneous NOx measurements before and after the catalyst unit, there must be two sets of measuring devices. Also, the calibration of the instruments requires calibration gases in pressure vessels.

The auxiliary equipment and tools must be at hand and easily available. There is actually amazing amount of hardware needed, including rolls of cable and pipeline, chemicals, laptops and so on.

Usually the measurement equipment station is quite near the exhaust channels. These positions are usually small and confined. The electricity outlet can be far away, and the first thing to do is to find a way to plug in. The completion of the station from boarding to standby takes up several hours. The typical setup of the equipment station is illustrated in picture 1.

Picture 1. Equipment station with calibration gas vessels

Connection to the exhaust inlets

The pipelines and tubes for the exhaust sampling are installed simultaneously during the preparation of actual measurement instruments. The distance from the equipment station from the exhaust inlet can be dozens of meters. The passage of the pipeline is not a straight line and usually it passes through a complex maze of ship equipment and narrow boardwalks. The connection and underpinning of the pipelines must be secured and there must not be any bents blocking the gas flow. The vertical offset of the equipment station and an inlet can be several floors.

The exhaust gas is hot and the surroundings of the inlet to the exhaust channels are hot too. The mounting of the pipeline mouthpiece is usually insulated with a piece of fiberglass. This also stops the exhaust gas flow out of the exhaust channel. Example of inlet connection is presented in picture 2.

Picture 2. Exhaust channel inlet connection with temperature monitoring

Control room data gathering

The final calculation for the actual emission measurement report requires data from the control system of the ship. The control data includes various parameters, for example information about the fuel consumption, engine load and run time logs and logs of turbocharger operation. Also, a bunker certificate of the fuel used is requested from the control room.

The output of the control system can be a detailed log with all necessary information or, typically, a minimum set of information for the immediate ship operation purposes. The information can be provided as a data file or a print-out from the operator console. For special purposes there are separate logs which can be accessed by request. An example of separate log is catalyst urea consumption and bunkering log. The control room data acquiring is one of the most challenging parts of the measurement as the ship control systems are designed for actually running the ship instead of detailed data logging. Sometimes the data simply is not available only by monitoring the meters and writing down the values of analogue meters.

Measuring

The actual measurement begins with the calibration of the equipment. The calibration is repeated when measurement arrangement is changed, and a final calibration is also conducted at the end of the measurement.

The measurement process records measurement information for a determinate period. A reading of current value is usually taken once per minute. The measurement process records data to a data logger and it is assisted by a field computer with special software. The measurement keeps accurate track of date and time, and all measurement values are time stamped. Multiple samples of the exhaust gas are taken and absorbed to liquid for later laboratory analysis.

Measurement follows the measurement plan. The plan defines the order of the measurement targets and assures that all the needed information is gathered and the required samples are taken. Every step of the measurement is also written down manually together with the periodic measurement value verification notes.

Dismantling

At the end of the measurement the gathered data is secured by back-up procedure. The equipment station, pipelines and all other material are packed for the transport. The need to make the measurement period as long as possible sometimes causes the dismantling to be done very late, just before the ship is arriving to the port. The ship may only be loading and unloading passengers and head back to the sea after one hour, which makes the departure of the measurement crew quite rushed.

Measurement report

The emission measurement report is written after the measurement run. Usually there are several samples to be analyzed in laboratory before all the necessary information is ready to be processed to report.

The data gathered form the loggers and computers used onboard is transferred to readable form and the integrity of the data is checked. The time stamps and manual notes are checked. The information is then processed with special calculation templates and the results are written down.

The report is intentionally short. The measured and calculated values are presented as simple as possible. This serves most of the purposes, as the measured amounts of substances are in well-known scale and do not usually need further explaining. Table 1 gives an example of the simplified format of the tables in reports. For special needs there is of course possibility to make many kinds of analysis of the gathered information and include more detailed content to the report.

The measurement results are archived for later use. The measurement archive serves as a reference point for example in comparison of the earlier emissions measurements of same ship or the same engine type.

Table 1. Excerpt of a one table of measurement report.

Engine N

Load
(%)

NOx dry
(ppm)

NOx
(mg/(n)m3)

NOx
(g/kWh)

ME 1

80

483

980

± 7 %

5,93

± 10 %

ME 2

73

380

767

± 7 %

3,76

± 10 %

ME 4

70

901

1822

± 7 %

9,55

± 10 %

ME 4

80

417

844

± 7 %

4,36

± 10 %

AE 1

42

906

1830

± 7 %

10,02

± 10 %

Conclusions

The scientific research is based on empirical studies. Empirical studies can take many forms or shapes, and one of these shapes is the rare occupation of onboard measurements. Kyamk emission measurement laboratory perceives itself as an instrument in service of higher research by providing the empirical findings and first-hand information from actual situations.

There are several approaches to the marine emission measurements onboard. The methodology used depends on the objectives of the measurement. The Kyamk emission measurement laboratory has chosen to streamline the process and concentrate to elementary tasks. The measurement repertoire is carefully chosen and limited to the necessary and most useful measurement subjects. The process of conducting the measures has developed to a robust and reproducible form.

Ships are a very special working environment. The completion of the of the precise laboratory measurements onboard a ship with dismountable laboratory is, indeed, a challenging line of work.

Author

Jouni-Juhani Häkkinen, Technology expert, Kymenlaakso University of Applied Sciences, Finland, jouni-juhani.hakkinen@kyamk.fi

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