PRACTICAL CONSIDERATIONS FOR THE …...Key considerations to be addressed during the Engineering...

1 | PRACTICAL CONSIDERATIONS FOR THE INSTALLATION AND OPERATION OF EXHAUST GAS CLEANING SYSTEMS

PRACTICAL CONSIDERATIONS FOR THE INSTALLATION AND OPERATION OF EXHAUST GAS CLEANING SYSTEMS December 2019

CONTENTS OVERVIEW ............................................................................................................................... 3

REGULATORY REQUIREMENTS ............................................................................................. 3

Scrubber as Equivalency ........................................................................................................ 4

PLANNING ................................................................................................................................ 5

Space Constraints .................................................................................................................. 6

Power Availability ................................................................................................................... 7

PROCUREMENT ....................................................................................................................... 7

ENGINEERING .......................................................................................................................... 8

Materials ................................................................................................................................. 8

Backpressure ......................................................................................................................... 8

System Configuration and Vessel Integration ......................................................................... 9

Sludge Handling ..................................................................................................................... 9

Class and Statutory Approval ................................................................................................. 9

INSTALLATION ........................................................................................................................11

Onboard Preparation .............................................................................................................11

On Shore Preparation ............................................................................................................11

Work in Dry Dock and at Quayside ........................................................................................12

Structure ................................................................................................................................12

Electrical ................................................................................................................................12

Piping and Seachest ..............................................................................................................12

Stability ..................................................................................................................................12

COMMISSIONING ....................................................................................................................13

Additional Consideration Post January 1, 2020 .....................................................................14

OPERATION .............................................................................................................................14

ABS SUPPORT ........................................................................................................................14

ABS AND IMO SCRUBBER-RELATED PUBLICATIONS .........................................................15

APPENDIX I – PRACTICAL CONSIDERATIONS ON OPERATION OF SCRUBBER ...............16

APPENDIX II – RESTRICTIONS ON OPEN LOOP SCRUBBER AND WASHWATER DISCHARGE ............................................................................................................................24

TABLE OF CONTENTS


PRACTICAL CONSIDERATIONS FOR THE INSTALLATION AND OPERATION OF EXHAUST GAS CLEANING SYSTEMS

OVERVIEW The IMO 2020 global sulfur limit requirements are effective from 01 January 2020. Common compliance options to address these requirements are the use of compliant fuels, the use of alternative fuels with a sulfur content less than 0.5% such as LNG, or the installation of an exhaust gas cleaning system commonly known as a scrubber. To help Owners and Operators in the scrubber installation process, ABS first published this document in 2018. The document introduced the regulatory requirements and outlined items to be considered during the planning, procurement, engineering, installation and commissioning for scrubber installation, and briefly discussed considerations for the operation of scrubbers. This revised version further elaborates on the considerations for the operation of a scrubber based on the latest Regulations and includes feedback on the lessons-leanred from Owners and Operators of ships with an operating scrubber. This feedback is listed on Appendix I.

REGULATORY REQUIREMENTS In designated Emission Control Areas (ECAs), compliance with a sulfur limit of 0.1% has been in force since January 2015. Beginning 01 January 2020, a global 0.5% sulfur limit is in effect. In addition to IMO requirements, there are regional and local requirements that may be applicable as seen in Figure 1 below.


Figure 1: Examples of Regional and Local Scrubber Related Regulations

Scrubber as Equivalency As indicated in Figure 1, an approved scrubber system is commonly accepted as an equivalent alternative for meeting the fuel sulfur limit requirements. The most common installation is a wet scrubber system with the following three option types: open loop, closed loop and hybrid. The three scrubber types operate on the same principle: the washwater is injected into the scrubber tower through the spray nozzles arranged in an optimized pattern to create a turbulent environment to maximize the surface area of sprayed water in contact with the exhaust gas. Sulfur Oxides (SOx) in the exhaust gas is absorbed in the water and becomes acidic which is neutralized by the naturally existing or artificially added alkali in the washwater to form sulfites and is further oxidized to a sulfate. In an open loop system, seawater with naturally existing alkali is used for scrubbing and discharged back to sea. Treatment of the washwater effluent is typically optional provided the effluent meets the criteria, which includes pH, PAH and turbidity, for discharge in the applicable IMO or regional/national requirements. The system typically incorporates an automated arragement to adjust the washwater flowrate when operational parameters change such as increase of engine load which increases the exhaust gas flowrate, making the SOx emission level and washwater to be within the required limit.


For a closed loop system, fresh water is typically treated by adding sodium hydroxide (NaOH) to achieve the required alkalinity for scrubbing and neutralization. The washwater effluent will be treated before being re-circulated to the scrubber and any losses are made up with additional freshwater. A small quantity of the washwater effluent is bled off to a treatment plant before discharge to sea.If discharge is prohibited, the effluent is routed to a holding tank. Sludge removed by the treatment plant will be stored onboard for disposal ashore. For closed loop systems, the washwater circulation rate typically remains unchanged. When operational parameters such as engine load changes, the automation system will adjust the dosing amount to the circulation washwater. In addition to scrubber and associated auxiliaries, a closed loop system will include equipment for washwater treatment, sludge handling and chemical dosing (typically Sodium Hydroxide, NaOH). Hybrid systems can operate in either open or closed loop mode as needed.

PLANNING Effective planning for installation of a scrubber onboard a vessel should consider a feasibility evaluation, lead time for the supply of the scrubber, scope of structure and system modification, engineering evaluation and class approval, fabrication, installation and integration, and testing, commissioning and demonstration of compliance. Scubber installation typically involves the shipowner, scrubber supplier, engineering company and shipyard. It is important to have defined roles for each party during the various stages of installation. As an example, the equipment provider may deliver the basic design and system material specification, the engineering company or shipyard may develop construction drawings, while the shipyard carries out equipment installation and system integration. For existing vessels, the time spent to retrofit a scrubber system depends on several factors with the equipment supply lead time and the availability of a retrofit yard often being critical. Effective planning may allow some of the required steps to be performed concurrently with the possibility for much of the work to be completed before the ship arrives at the retrofit yardwhich can significantly reduce time spent in the yard. Drydocking needs to be taken into consideration if it is necessary to enlarge the existing seachest, or an additional seachest is needed to meet the demand for washwater for the scrubber. If feasible, the retrofit activity may be aligned with the statutory renewal survey or other modification work. Two major items to be addressed during the initial planned phase are space constraints and power availability.


Space Constraints Scrubbers are large pieces of equipment. Space to accommodate a scrubber and its auxiliaries is one of the challenges of scrubber retrofitting.

Figure 2: Scrubber

Typically, closed loop and hybrid systems are more complicated than open loop systems. More space is required for the storage of dosing chemicals, circulating water, bleed-off water and washwater residues. Additional space is necessary to accommodate equipment such as heat exchangers and water treatment units. The capacity of a circulating water tank is typically the volume of water pumped by a circulation pump in 1.5 minutes with 10% margin, plus the pipe volume of the circulation system. The bleed water holding tank could be a few hundred cubic meters depending on the duration that the system operates in zero discharge mode when overboard discharge of washwater is prohibited. To accommodate the scrubber towers and gas sampling equipment, enlargement of the funnel is often required.


Power Availability Power availability onboard an existing vessel is another key factor to be considered. Typical additional power demand can be around 1.5% of the rating of the engines the scrubber serves. An electrical load analysis will help to determine if the ship’s existing power plant has adequate capacity for the additional power demand of the scrubber. The evaluation is to consider various operation modes of the ship, including normal sea going, maneuvering and cargo loading/offloading. If it is determined that an additional generator is needed, the installation of a scrubber may not be a viable compliance option.

PROCUREMENT Since a scrubber system is a ship-specific solution for sulfur emissions, the procurement process should ensure the system is suitable for the vessel needs. This should consider the operating profile of the candidate vessel. Key items to be addressed are:

• Technical limitations and operational restrictions

• Emission monitoring technology

• Footprint and weight

• Power requirement under all operating conditions

• Materials of scrubber chamber and accessory components/systems

• Regulatory approval status

• Redundancy and worldwide service availability


ENGINEERING Key considerations to be addressed during the Engineering phase include material suitability, backpressure, system configuration and vessel integration, and sludge handling arrangements.

Materials The materials used in the construction of the scrubber and the accessory components are important for the reliability and durability of the system. They should be suitable for the potential high temperatures and corrosive operational conditions. The table below summarizes typical materials for different systems, equipment and components.

Component Common Material

Scrubber reaction chamber Super austenitic stainless steel - SMO 254 (6 Moly)

Washwater lines (effluent, bleed-off) GRP (glass reinforced plastic)

Super duplex stainless steel

Water lines (scrubbing, cooling, reaction, makeup

water)

GRE (glass reinforced epoxy)

Carbon steel with PE (polyethylene) lining

Alkali (NaOH) supply Stainless steel - SS 316L

Sludge tanks Plastic

Steel with synthetic coating

Sludge lines GRE, FRP or GRP

Valves (Exhaust, bypass, isolation) Nickel alloys

Table 1: Common Scrubber Materials

Backpressure The installation of a scrubber may impact the operation of the engine if excessive exhaust backpressure is generated. It is important to verify during the evaluation of a candidate scrubber system that the backpressure is within the limits set by the engine manufacturer. Increase of exhaust backpressure may result in additional fuel consumption due to lower turbocharger efficiency, increased component temperatures, and cause increased wear. In addition, Nitrogen Oxides (NOx) emission may be increased. It is to be noted that scrubber systems that cause diesel engines to operate outside the exhaust backpressure limits detailed in the approved IMO Annex VI Regulation 13 Technical Files may invalidate the emissions certification and will require a re-approval of the engine NOx certification by the Flag Administration or Recognized Oraganization (RO) responsible for the original certification. Exhaust gas fans may be used at the scrubber outlet to compensate for any additional backpressure, however the addition of more equipment may increase the required power and maintenance over the life of the system.


System Configuration and Vessel Integration Multi-inlet scrubbers are typically installed so one scrubber can serve multiple engines/boilers. Such integrated systems require isolation and bypass arrangements so that any engine not in operation can be isolated, or in case of scrubber failure, the scrubber can be bypassed if they are not designed for operation in a dry condition. As illustrated in Figure 3, the isolation valve (tag no. 7) and bypass valve (tag no. 6) should not both closed, otherwise, the excessive backpressure may cause the engine to stall. A proper control logic and interlock arrangement should be provided. The scrubber system design is to consider any abnormal condition that may occur during the operation, for example, excessive high temperature, lack of washwater or potential of scrubber flooding. Automatic shutdown should be incorporated in the monitoring and control system as a safety measure.

Sludge Handling For closed loop or hybrid systems, sludge will be generated from the washwater treatment system. Under IMO Guidelines for Exhaust Gas Cleaning Systems, MEPC.259(68), such sludge is not to be discharged to sea or incinerated onboard. Typical tanks of 0.5 – 1 cubic meter per megawatt (MW) of engine power are specified. A sludge dewatering system may be provided to dry the sludge and minimize the volume, eliminating the need for a sludge tank on board. Sludge can be stored in Intermediate Bulk Containers (IBC) or barrels and transferred ashore.

Class and Statutory Approval A scrubber system requires approval from both a statutory and Class perspective and includes the review of the equipment as well as the review of the onboard installation. From a statutory perspective, the IMO Guideline for Exhaust Gas Cleaning Systems, MEPC. 259(68), outlines the process including approval Schemes A and Scheme B as depicted in Figure 4. Scheme B is typically used for the approval of scrubber installations on both new construction and retrofit projects.

Figure 3: Bypass and Isolation for Scrubber


Figure 4: Outline of Exhaust Gas Cleaning System Approval Scheme

Compliance with the SOx emission limit is through in-service continuous monitoring of the Sulfur Dioxide/Carbon Dioxide (SO2/CO2) ratio in the exhaust gas, and the condition of discharged washwater. Upon satisfactory initial survey of the installation, and verification of the performance of the monitoring system, with the concurrence of the Flag Administration, the scrubber will be annotated in the Supplement to the International Air Pollution Prevention (IAPP) certificate as the equivalent means for meeting fuel sulfur limit requirements. The Flag administration is to notify their acceptance to the IMO for inclusion in the IMO GISIS database for each ship-specific approval.


From a Classification Society perspective, the requirements in the ABS Guide for Exhaust Emission Abatement related to the safety aspects of the system include:

• Configuration and vessel integration

• Exhaust by-pass arrangement

• Prevention of flooding

• Vessel Stability

• Electrical load analysis

• Piping system

• NaOH supply system

• Safety Shutdown In addition, ABS offers an optional class notation, EGC-SOx, which can be assigned if the applicable requirements in the ABS Guide for Exhaust Emission Abatement are fully complied.

INSTALLATION For existing vessels, preparation for installation can be completed onboard while the vessel is in operation, onshore before the vessel arrives at the yard, or when the vessel is in the yard. The work onboard will typically require modifications to the structure, electrical and piping systems.

Onboard Preparation Some preparation work onboard may be carried out while the vessel is in operation. This includes the installation of piping, cabling and foundations for seawater pumps and sealing air fans. This can help reduce the time required for retrofitting at the yard.

On Shore Preparation Typically, when a new funnel block is required, it is common practice to have the block constructed with the scrubber and associated piping and electrical installed within the new block. Piping for the engine room can be prefabricated for installation.

Figure 5: Seawater Pumps for Scrubber System in Engine Room


Work in Dry Dock and at Quayside The additional water demand for scrubber systems may require the existing sea chest to be enlarged, or an additional sea chest to be added. In such cases, dry docking may be necessary. Integration of the scrubber system with the shipboard system include the exhaust piping system and the control and monitoring system. The control and monitoring panel is typically installed close to the engine control station. Depending on the scrubber system, an engine load signal may be needed as input to the scrubber system for adjusting the washwater flowrate through VFD (variable frequency driving) pump or throttling valve in washwater supply line. Due to the corrosive nature of washwater effluent, plastic pipe (FRP or other similar material) are commonly used. Plastic pipe connection work should be in accordance with the manufacturer’s installation guidelines and carried out onboard by qualified personnel.

Structure Structural modification associated with scrubber retrofitting is typically related to creating the space needed for the installation. Commonly, the funnel requires modification to accommodate the scrubber and the associated exhaust bypass pipes. Equipment, piping and ventilation ducts may need to be rearranged for the installation of accessory equipment/system. For closed loop systems, space for storage of processing water and chemicals and accommodation of additioanl equipment may take up some cargo space.

Electrical In addition to electric load analysis, an electrical coordination study and short circuit analysis to verify the integrity of the power supply system may be needed.

Piping and Seachest Piping modification involves sea chest enlargement or adding additional sea chest if existing sea chest cannot meet the water demand of the scrubber system. Overboard discharge for washwater will need to be added. The pipe between overboard discharge valves and the side shell need to be of metallic material as required by class Rules. This pipe could be subject to severe corrosive effluent. Carbon steel with plastic lining or high-grade stainless steel should be considered.

Stability Stability and lightship weight need to be evaluated due to the additional weight of the scrubber system. In general, if the change in lightship displacement exceeds 2% of the lightship displacement from the most recent approved lightship data and/or the change in lightship Longitudinal Center of Gravity (LCG), relative to the most recent approved lightship data, exceeds 1.0% of the Length Between Perpendiculars (LBP), a stability test may be required on the vessel and stability calculations would need to be revised to indicate the changes.


COMMISSIONING Commissioning of a scrubber system includes calibration of the monitoring and control system, functional testing, and performance evaluation of the complete system. Crew training may also be conducted during the system commissioning phase. Commissioning can be time consuming. One option is to separate the commissioning and installation process. Once installation in the yard is completed, the ship may return for service with commissioning planned in the future. This can help to decrease the off-hire time. Arrangements would need to be made to ensure the vessel was operated in compliance during the interim period. Preparation for commissioning should consider:

• Development and review of a test plan by Class

• Onboard verification of the monitoring and control system sensors. These sensors should be preset at the manufacturer’s plant; however they may require some calibration once the system is installed onboard the vessel, such as zero and span calibration to confirm gas analyzers.

• Availability of fuel with the sulfur content corresponding to the design sulfur limit of the scrubber system for performance evaluation

• Availability of the sampling kit for the washwater effluent, typically provided by the testing laboratory

Functional testing is to be carried out to verify the integrity and operability of the system including the control, monitoring, alarm and safety system. This includes the interlock arrangement on the exhaust pipes bypassing the scrubber. Performance testing will involve testing at quay side and during sea trials. Although not required for the Scheme B approval approach under the IMO Guidelines, many owners/operators have chosen to carry out testing to evaluate the performance before the scrubber system is put into operation. This includes the measurement of the SO2 to CO2 ratio, and the properties of washwater including pH, PAH, turbidity and nitrates. The test for emission limit verification can be time consuming. IMO Guidelines (Section 4.3.6) require the test to be done for at least 4 engine load points. At each load point, it may take proximately 20 to 30 minutes to get the load steady, and an additional 10 to 15 minutes to get the stabilized reading on the emission monitor. Scrubber system commissioning has taken two to three days during sea trials for some past projects. The accuracy of the emission monitor may be validated by testing the exhaust gas sampled at the exhaust stack with a portable analyzer. The pH value of washwater could be measured 4 meters from overboard discharge at quay side when the vessel is stationary with generator engines in operation. The corresponding pH value


measured at overboard discharge is set as the minimum pH limit. Alternatively, the pH limit monitored at the overboard may also be determined by calculation method following IMO Guideline criteria. For U.S. EPA requirements, the pH value needs to be measured at the overboard discharge.

Additional Consideration Post January 1, 2020 It is anticipated that owners and operators will continue to adopt and install SOx scrubbers long after the implementation of IMO 2020 global sulfur limit requirements. Planning for the installation and operation may need to consider the following and discuss the same with flag Administration and their Recognized Organization to avoid any unexpected delay for the operation of the scrubber:

• Acceptance of HSHFO for scrubber commissioning

• If HSHFO is to be used for commissioning and no such fuel is onboard, permission for receiving such fuel

• Permission for the issuance of a full term or conditional IAPP certificate to include scrubber upon completion of commissoning pending result of washwater nitrate testing

OPERATION In service operation should consider manning and crew intervention, understandng the system design limitation, preparation for startup, automatic and safety functions, record keeping for demonstration of compliance, contingency measures in case system malfunction, port state control enforcement, and maintenance and repair of the system. Appendix I of this document addresses the practical consideration of the above including feedback received from Owners/Operators who have installed and operated a scrubber. Some regional, national and local authorities impose restriciton to the discharge from scrubber system. It is important to be aware of such restriction. Appendix II summarizes the known restrictions for ready reference.

ABS SUPPORT ABS can assist owners and operators with reviewing the appropriate compliance options given the specific operating profile for each of their vessels. With regard to scrubbers, ABS can support owners and operators with understanding the available technology, life-cycle costs and operational impact


ABS AND IMO SCRUBBER-RELATED PUBLICATIONS • ABS Advisory on Exhaust Gas Scrubber Systems (July 2018): This Advisory

summarizes the regulatory requirements applicable to scrubbers and provides an overview of available technologies.

• ABS Exhaust Emission Abatement Guide (April 2019): This Guide outlines the requirements to be applied to exhaust emission abatement systems fitted to ABS classed vessels primarily covering SOx scrubbers, Selective Catalytic Reduction (SCR) systems, Exhaust Gas Recirculation (EGR) arrangements, and Exhaust Emissions Monitoring Systems (EEMS) associated with the aforementioned emission abatement systems.

• MEPC.259(68), 2015 Guidelines for Exhaust Gas Cleaning Systems

• MEPC.1/Circ. 883, Guidance on Indication of Ongoing Compliance in the Case of the Failure of a Single Monitoring Instrument, and Recommended Actions to Take if the Exhaust Gas Cleaning System (EGCS) Fails to Meet the Provisions of the 2015 EGCS Guidelines (Resolution MEPC.259(68))

• MEPC. 321(74), 2019 Guidelines for Port State Control under MARPOL Annex VI Chapter 3


APPENDIX I – PRACTICAL CONSIDERATIONS FOR OPERATIONS OF SCRUBBERS

A. Manning and Crew Intervention Scrubbers are new systems for many of the crews onboard. Crew need to be assigned responsibility for the operation of the system. Although it may vary depending on the operator, typical assignment and required intervention are as below

1. Typical installation and commissioning involvement: • Chief Engineer and 2nd Engineer • 3rd/4th Engineers and electrical officer

2. Typical operational activity in-charge: 2nd Engineer

3. Typical crew intervention: • start-up and shutdown • switching between open and closed loop mode (for hybrid system) • when an alarm condition occurs • in case sulfur content of fuel used exceeds the design limit

B. Understand the System Design Limitations Understanding the system design limitations is important for the safe and efficient operation of the scrubber system. Typical design limitations are summarized below. The ETM-B may be referred to for ship specific information.

1. Scrubber design capacity, e.g., in term of exhaust gas flow (or respective FOCU rating)

2. The maximum sulfur content in fuel the system is designed for

3. Whether the system is designed for dry operation

4. Whether the system is designed for meeting U.S. VGP washwater discharge criteria

5. Whether the scrubber’s alarm and monitoring system (AMS) is linked to ship’s AMS

6. Sludge tank and zero discharge tank capacity for closed loop operation duration

7. Maximum exhaust gas temperature before scrubber

8. Maximum exhaust gas temperature after scrubber

9. Maximum gas pressure drop across the scrubber

10. Maximum inlet exhaust gas pressure

11. Maximum washwater flow

12. Minimum washwater alkalinity

C. Preparation for Startup The preparation for the start-up of a scrubber system may vary by scrubber type.The safety precautions focus on system readiness for a trouble-free operation and are defined by the maker. The operational sequences are especially important, and maker’s instructions need to be followed strictly. Typically items found on the operators check list are summarized below.


A short duration for transitory deviation of SO2/CO2 ratio from compliance value is expected. This duration typically lasts from one to few minutes, not longer than 15 minutes.

1. Power the control panels and see all alarms activated and acknowledge them. Verify alarms are linked to vessel’s AMS system where applicable

2. Readiness of sealing air supply lines to be confirmed to ensure no valve on supply line is in closed position

3. Staring fans for air supply (damper valve isolation) at lower RPMs and see the rotation/direction is in good order to see if any abnormality is arising

4. Check the position of by-pass and intake damper. In some cases, those might be manually operated while some makers having auto interlock. In case of manual operated damper valves, correct positions need to be checked before starting operation. Where remote control is provided, check the operation from the panel is working properly and see the position status on the panel

5. Check the water supply lines and valves as applicable for the correct position during the operation including the sea chest valve (Open position). Check that washwater drain valve including overboard discharge valve are in open position. In case any valve is provided with remote control function, then check the operation remotely

6. In case chemical handling is required (closed loop), proper PPE is used for handling as required by maker’s instruction

7. Readiness of the sea water line (open loop), FW line (Closed loop) and chemical additive supply line (closed loop). Crew need to ensure that all lines are ready for usage upon running of the pumps

8. Running the supply pumps as applicable at lower RPMs and keep them to run for a while at lower load which will also de-aerate the pumps

9. If non-metallic packing beds are fitted in the scrubber chamber, those non-metallic material might be sensible to hot exhaust gas. Makers recommendations/instructions are to be followed to avoid the system running in dry condition to prevent any damage

10. Once all is in good order, then supply pump RPM can be increased to desired level based on the FOCU load

11. For closed loop system running, the wash water cleaning/treatment unit may require to be run as well

12. Once system is in operation and there is no abnormal indication, then engineer in charge is to check around in E/R to see: a) No excessive vibrations on the pipes or components b) No leakages on the liquid lines c) No abnormal/excessive noise d) Chemical holding (e.g. NaOH tank) tank level is sufficient for continuous operation


D. Automation and Safety The scrubber system is typically incorporated with automatic control and safety functions for the safe and effective operation of the scrubber and the fuel oil combustion unit (e.g., engines) it serves. Typical operational parameters and alarm/safety conditions are listed below. They may vary depending on specific design.

Monitored Parameters, as applicable

Display Alarm Condition

Safety Condition – auto EGC shutdown and EGC bypass

Exhaust fan motors Running Stop

Exhaust bypass or isolation valves, where provided

Position

Control-actuating medium of the exhaust bypass or isolation

valves

Running Failed

Exhaust gas temperature before EGC unit

X High X (High-High)

Exhaust gas temperature after EGC unit


Exhaust gas pressure after FOCU unit


Differential pressure across EGC unit


EGC washwater pumps Running Stop

EGC washwater system valves Position

Control-actuating medium of the EGC washwater valve

Running Failed

EGC system washwater supply pressure

X Low X (Low-Low)

EGC system washwater supply temperature


Water level in wet EGC unit X High X (High-High)

Control and safety system power supply

Running Failed

Emergency shutdown X X X

Washwater Turbidity difference X High

Washwater PAH difference X High

Washwater pH X Low


E. Residue/Sludge Disposal Sludge generated by the scrubber is not allowed to be discharged to sea or incinerated onboard. Such sludge needs to be delivered to onshore reception facilities. The IMO Database on Global Integrated Shipping Information System (GISIS) provides information on the ports and terminals with reception facilities.

In addition, individual Port Authorities may have specific policies for the disposal of sludge. As an example, Singapore MPA (Maritime and Port Authority) has issued a circular which classifies scrubber sludge as toxic industrial waste (TIW) and requires that the sludge be collected and managed by licensed toxic industrial waste collectors (TIWCs). Owners and operators with vessels incorporating a closed loop system are advised to check with the Port Authority they plan to visit for the sludge disposal policy IMO GISIS Database for ports/terminal with reception facilities: https://gisis.imo.org/Public/MARPOL6/Notifications.aspx?Reg=17.2

F. Record Keeping for Demonstration of Compliance For systems under the Scheme B approval, the emission level of SO2 (ppm) to CO2 (% v/v) ratio, and the washwater discharge properties are to be automatically monitoring and recorded whenever the scrubber system is in operation. Typical documents and data record for demonstration of compliance are summarized below. Port State Control (PSC) and local authority may request additional information

1. IAPP Certification with scrubber (EGCS) included in Supplement Form

2. Onboard documents for scrubber a) SOX Emission Compliance Plan (SECP) b) EGCS Technical Manual (ETM-B) c) Onboard Monitoring Manual (OMM) d) EGC Record Book or Electronic Logging System

3. Record of data a) Exhaust gas SO2(ppm)/CO2(%) b) Washwater pH, PAH, Turbidity and temperature c) Universal Time Co-ordinated (UTC) and ships position by Global Navigational Satellite

System (GNSS) d) Nitrate discharge data and analysis certificate Items under a) through c) are recorded by recording device automatically, while item c) is the test result of washwater samples retained onboard as part of EGC Record Book

4. Daily spot checks of the operational parameters recorded in EGC Record Book or Electronic Logging System

https://gisis.imo.org/Public/MARPOL6/Notifications.aspx?Reg=17.2


5. Record for the storage and disposal of washwater residues/sludge (closed loop) - to be in the EGC log

6. Vessels subject to U.S. EPA Vessel General Permit (VGP), records of wash water sampling and testing result retained onboard for 3 years as per 2.2.26.2.3 of Final 2013 VGP: a) Dissolved and Total Metals b) PAHs c) Nitrate-Nitrite d) pH

G. Contingency Measures In the case when a scrubber system malfunction last more than one hour or repetitively malfunctions, ship should notify the flag and port State’s Administration for instruction. IMO Document MEPC.1/Circ.883 provides detailed Guidance for the two cases as summarized below for the key steps to be taken.

1. In the Case of scrubber Malfunction

a) Identify and remedy the malfunction as soon as possible after the malfunction is identified (e.g. alarm is triggered) following the maker’s recommendations

b) The malfunction should be included in the EGCS record book including the date and time the malfunction began and, if relevant, how it was resolved, the actions taken to resolve it and any necessary follow up actions

c) If the malfunction cannot be rectified within one hour then it is regarded as an accidental breakdown and the vessel should changeover to compliant fuel. If the ship does not have compliant fuel oil or sufficient fuel oil, a proposed course of action to bunker compliant fuel or carry out repairs should be communicated to relevant authorities including the ship’s flag and port State’s Administrator for their agreement

2. In the Case of Monitoring System Malfunction, Interim Indication of Ongoing Compliance

a) Log of the malfunctioning of the monitoring equipment

b) Recording of the remaining parameters together with the record of the sulfur content of the fuel oil used in the affected FOCU from the time when the malfunction started

c) The malfunctioning monitoring equipment should be repaired or replaced as soon as practicable

H. Port State Control (PSC) Enforcement A scrubber accepted by the flag Administration as equivalency for fuel sulfur limit compliance is subject to the inspection by Port State Control (PSC). As stated in the MEPC. 321(74), the inspections could include initial inspection and more detailed inspection as outlined below

1. Initial inspections, including the following: a) Evidence that the ship has received an appropriate approval for scrubber, e.g., Supplement

to IAPP certificate;

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b) Evidence that the ship is using scrubber for fuel oil combustion units on board as identified on the Supplement of the IAPP certificate, and that compliant fuel oil is used in equipment not covered by scrubber;

c) BDNs on board which indicate that the fuel oil is intended to be used in combination with scrubber; and

d) Documentation for action taken in the case where an scrubber is not in compliance with relevant requirements due to malfunction or breakdown, or the malfunction of the monitoring system for emission or washwater discharge, including Notification to the ship’s flag with copies to the authority of the relevant port of destination.

2. Findings such as listed below may be considered “clear grounds” to conduct a more detailed inspection a) Missing required documents and certificates, b) Malfuncing or serious deficiencies in scrubber, c) The scrubber has not been used as required, d) The master or crew are not familiar with the operation of the scrubber, e) Receipt of a report contaning information that the ship appears to be not compliant, e.g.,

information from remote sensing surveillance of SOx emission. 3. More detailed inspections - typical items

a) Installation and operation - the scrubber installed and operated, together with its monitoring systems, in accordance with the associated approved documentation

b) Proper functioning - the system is properly functioning, is in operation, and continuously monitored

c) Records demonstrating compliance including emissions ratio, pH, PAH, turbidity readings and operation parameters

d) Operational procedures - confirming that the master or crew are familiar with the correct operation of scrubber together with any applicable monitoring and recording, and record keeping requirement

4. Detainable deficiencies, such as a) Absence of valid IAPP Certificate b) Absence of an appropriate approval for the scrubber c) The sulfur content of any fuel oil being used on combustion units not connected to an

scrubber exceeds the limits stipulated in MARPOL Regulation VI/14 d) Non-compliance with the relevant requirements while operating within an Emission Control

Area for SOX and particulate matter control e) The master or crew are not familiar with essential procedures regarding the operation of

scrubber I. Feedback and Lessons Learned for Scrubber Installation and Operation

Feedback and lessons learned are collected from the ships that are operating the system. The information summarized below intended for the improvement of the practice for the installation and operation of a scrubber system.

1. Installation and commissioning of newly installed system a) Extended test period due to lack of test plan and pre-commissioning. Follow approved test

plan and complete necessary pre-commissioning


b) Washwater carryover by exhaust gas, most likely due to inappropriate exhaust gas flowpath. This was identified on the installation of some newly designed system. Flowpath optimization and demister design modification could help to eliminate such problems

c) Unexpected high exhaust backpressure, likely due to undersized scrubebrs, sharp bend in exhaust piping, water spray resistance or failure of bypass-isolation valve interlock. It is recommended to improve the design though appropriate simulation for back pressure evaluation

d) Operation interruption (e.g., wash water supply), due to the clogging of filters in supply piping. Redundancy may be considered, and failure modes and effect analysis may be carried out

e) Out of compliance performance (wash water pH, SO2/CO2 ratio) could be due to inadequate washwater, low pH of supply water and inappropriate water spray pattern. Improvement of design, verification of the design through CFD simulation and verification of supply pH are to be considered

f) Poor reliability of monitoring system including instrument malfunction. Issues identified include the monitoring system is not for marine application, lack of calibration and inappropriate installation. Use of approved monitoring system, proven product and following maker’s instruction for calibration and maintenance are possible solutions

g) Loose nozzles, water/gas leak due to poor workmanship h) Noise caused by sealing fans annoying the crews. In some case, relocation of the fans was

needed

2. Hardware failure reported for system in operation:

a) Clogging of the sampling tubing with soot, which prevents proper SO2/CO2 analyzer readings

b) Clogging of the pressure transducers at the bottom of the pipe run with debris due to the inappropriate location of the sensors

c) Malfunction of the demister in the scrubber chamber due to the build-up of deposits

d) Faulty welds on piping system causing leakage of washwater e) Low grade stainless steel, e.g. SS316 for fittings inside the scrubber chamber, not be able

to withstand the corrosive operational environment, and require replacement within 3 years f) Excessive corrosion of the metallic pipe section at the side shell for washwater overboard

discharge

g) Exhaust gas sampling air pump not working properly

h) Scrubber uptake damper cannot be operated in manual mode

i) Failure of mechanical seals of washwater feed pumps

j) Failure of automation control PCBs 3. Major incidents causing engine shutdown and damage:

a) Human errors, i.e., crew operate the system in local mode disregarding control system

b) Main engine stall due to high backpressure in one case where failure of by-pass valve opening while scrubber uptake valve is closing. Cause identified is the failure of PLC


controlling the interlock of by-pass and uptake valve. Regular maintenance and testing in accordance with maker’s instruction should be practiced

c) Incident occurred to a vessel installed with inline scrubber. Since the exhaust enters from the bottom, a means is necessary to prevent/ detect buildup of water that could enter exhaust (coaming, high level alarm, etc.)

Lessons learned include: • the safety feature should be maintained regularly and tested following maker’s

instruction; and • the crew in charge of the operation is trained for appropriate starting procedure, e.g.,

checking the valve positions and safety features

4. Consumbles needed for scrubber operation: a) pH reference fluids for calibration/testing b) Calibration gases for measuring sensors

5. Other issues reported: a) Challenges for wastewater analyzation as the laboratories at the trade area may not be

able to analyze washwater parameters with ISO or U.S. EPA approved methods b) Insufficient instrument air quality affecting actuators c) High temperature in the scrubber chamber even the scrubber is bypassed due to leakage

of the bypass damper or defects in the sealing air system d) Accumulation of soot on packing beds or demisters


APPENDIX II – RESTRICTIONS ON OPEN LOOP SCRUBBER AND WASHWATER DISCHARGE Some regional, national and local authorities announced the restriction to the discharge of washwater from scrubber system. Although such restriction is commonly referrred to open loop system, it may in fact be applicable to closed loop system as such system does have certain amount of washwater discharged as bleed-off water. The known restrictions are summarized below for easy reference. Ship operators are recommended to clarify with the relevant local or port authorities before the ship’s visit to confirm for any discharge restriciton. Where the restriciton is imposed, ships may operate in zero discharge mode if they are fitted with hybrid system, or switch to compliant fuel for entering the relevant port and sea areas. Country Port/Sea Area Reference

Belgium All ports Item 6c of ESSF* & ICS** China China ECA water (12NM) China MSA Notice on the Implementation Plan of

2020 Global Sulphur Limit, 23 October 2019 Estonia Sillamae ICS** Denmark Aalborg ICS**

Frederecia Kalundborg

Finland Porvoo ICS** France Port Jerome ICS**

Seine River Le Havre Ambes Montoir Bordeaux

Germany Weser ports Item 6c of ESSF* & ICS** Elbe ports Kiel canal ports

Rostock Gibraltar Gibraltar ICS** Ireland Dublin port areas Notice to Mariners No. 37 Italy Ravenna ICS** Latvia Ventspills Item 6c of ESSF* & ICS** Lithuania Klaipeda Item 6c of ESSF* & ICS** Malaysia Malaysia Water (12 nm) Malaysia Shipping Notice MSN 07/2019 Netherlands Terneuzen ICS** Norway Glomfjord


Heroya ICS**, Section 14b of Regualtions of 30 May 2012 No. 488

Panama Panama Canal Notice to Shipping No. N-1-2019 Portugal Lisbon ICS**

Sines Leixoes Aveiro

Russia Primorsk ICS** St. Petersburg

Singapore Singapore MAP Guide for Ships Calling to Port of Singapore_sg_v9 & ICS**

Sweden Brofjorden ICS** Gavle Norrkoping Umea Sundvall Skelleftehamn

UAE Port of Fujairah Notice To Mariners No. 252 United States California: Scrubber not

allowed. 13 CCR, section 2299.2 Marine Notice 2017-1

Connecticut EPA VGP 2013 Section 6.5.9 United Kingdom

Finnart ICS** Hull Immingham Avonmouth Cardiff

* European Sustainable Shipping Forum (ESSF) **International Chamber of Shipping (ICS) Circular MC(19) 34 dated 15 March 2019

PRACTICAL CONSIDERATIONS FOR THE …...Key considerations to be addressed during the Engineering...

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