Challenges in the Installation and Operation of Ballast Water Treatment Systems Dr. John Kokarakis
The process 2
Questions to reply Enough capacity? Limitations Enough power? Safety? Gas Dangerous Zones Hydrogen removal? Monitoring-Alarms Ventilation? Low Salinity-Low Temperature (full flow) Training Risk assessment/hazid The after peak problem-harmonization Holding time, Dosage, Discharge limits 3
Installation questions: WHERE, HOW, WHAT Find a suitable location (minimize pipe and electrical runs) Integrate electrically into vessel system Engineer system for Class approval Integrate with existing pumps & eductors Isometric piping drawings (prefab) Usually available only 2D- Data Organization & logistics to minimize off-hire 4
Critical factors to installation Classification of the ship Type of vessel (tankers: additional safety issues) Standards (DIN, DIN EN ISO, JIS,...) differ in dimensions of joints, pipes etc. Small ships have less space in engine rooms Operating areas have to remain free (Gangway min. 600x2000 mm) Room height has to be considered Entrance to existing equipment for operation and maintenance, Stairways, emergency exits, man holes have to be kept free 5
Critical factors to installation Operating space for screws, bolts, nuts, handles,... No connections of fluid pipes above electrical devices Additional space for insulation Systems to be avoided (thermal oil) No welding close to / on because of tank coating tanks Standard pipe elbows with bending radius of 1xdiameter or 1,5xdiameter (1D, 1.5D) Angles of pipes always multiple of 15 Minimum distances between pipe bends due to fabrication 6
Documents for Class Approval P&ID of the ballast system including any connections to other systems (bilge, fire etc.) Arrangement of all units and auxiliary systems with critical importance for the functioning of the treatment system. Main Switchboard modification Updated electric load tables for all conditions Evaluation if new short circuit calculations are necessary. VFD will not for instance affect the short circuit currents. Control system block diagram and power supply arrangement List of controlled and monitored points/sensors Risk assessment Stability calculations.total weight added must be reported. Reinforcements needed due to the added elements. 7
The limitations Treatment process is limited by water temperature and salinity to achieve optimum performance. A heat exchanger might be used to raise the water temperature. Ballast can become contaminated by the residue/sediment in the tank. This may necessitate the treatment during de-ballasting. Management of dangerous gases is an important parameter to consider when installing BWTS. 8
Hydraulic constraints An orifice might be utilized to limit flow through the BWT system. In case of pump upgrade, assess the suitability of existing piping/flanges to the higher pressure in the system. Systems which treat ballast water during intake only, can utilize gravity discharge with provision for neutralization. 9
Installation Pointers Installation surveys to ensure that the BWTS is installed in accordance with the approved drawings and BV requirements. On-going surveys ensure correct maintenance and operation and record-keeping on board. Makers must provide information on whether system can generate hydrogen or other hazardous gases affecting ballast water tank coatings. Plastic pipes are to meet the fire endurance requirements of the BV Rules and Regulations and IMO Resolution A.753(18). Transfer of ballast water from non-hazardous to hazardous area may be accepted but not vice versa. Ballast from the APT is to be discharged to a hazardous area, piping is to be provided with two non-return valves in series and be at main deck level. Penetrations of engine/pump room bulkheads are in general not permitted. Spool pieces are removed after ballast transfer and the open pipe flanges be covered by blanking plates adequate for the service pressure. 10
Problems with filters Clogging Mechanical failure Corrosion Water hammer Damage due to foreign particles Lack of spares-moving parts Filters are very heavy!! Need robust supports Difficult to move About 10 m head loss (v 2 ) Fresh water washing 11
Filter impact on BWTS We believe that filters are the most challenging part of BWTS and also sine qua non. Filters remove/withhold the largest percentage of zooand phyto- planktons. 97% and 50% respectively. Many of the existing filters have inadequate self-cleaning abilities, resulting in serious clogging problems. If the filter clogs, the ship stops! Filter protection multilayer screens of varying mesh sizes prefiltering. Multiscreen solutions. 12
Filter dimensions - weight 13
Installation in Oil & Chemical Tankers If possible install in a hazardous area (pump room). Such systems must be explosion proof Moving parts that can cause static electricity are not installed in hazardous areas. Ballast tanks are hazardous areas. Systems might be installed in the engine room. Treated water can go to the ballast tanks through the main deck. 14
How to penetrate BHD separating safe/unsafe 15
Challenge: Sampling Maximize the representativeness of the water sample (especially for larger mobile zooplankton). Candidate locations in the discharge of the ballast pump (where turbulence is very high). Isokinetic sample from a pipe located at the center of the main ballast pipe is preferable than from a small pipe attached to the wall of the pipe. Inside diameter of the sampling pipe should be approximately 10% of the diameter of the ballast pipe or 1.5-2 times the computed isokinetic diameter. 16
Sampling purpose and sampling points For BWT standards, samples serve to confirm compliance (qualitative analysis) Preferred sampling point for BWT is at discharge of ballast water Sampling for BWE standards is usually from the ballast water tanks, taken trough man-ways, air or sounding pipes 17
Sampling 18
EPA VGP A) BW system functionality monitoring BW monitoring equipment calibration (sensors annually) Critical sensors more frequent (ph probes, TRO sensors, turbidity sensors, etc.) B) Effluent biological organism monitoring Biological indicators bacteria only (heterotrophic bacteria, E.coli, Enterococci) 2 times per year (1 time second year), records to be kept 3 years C) Effluent limitations for BWTS using Active Substances Discharge of biocides or residuals may not exceed instantaneous max limits (e.g. Chlorine 100 mg/l) Sampling 3 times in 180 days, then 2 times per year 19
Calibration Schedule Electrolyzer Level Switch (1) Drain Tank Level Switch (1) Pressure Indication & Transmitter for Gas Separator (1) Gas Detector (3) Seawater Salinity Sensor (2) Main Flow Transmitter (3) Level Indication & Transmitter for N.A Tank (1) TRO Sensor (3) Turbidity, color, or suspended solids can introduce positive interference
Ballast water monitoring-biomarkers Indicative analysis: means a compliance test that is a relatively quick indirect or direct measurement of a representative sample of the ballast water volume of interest. Detailed analysis: means a compliance test that is likely to be more complex than indicative analysis and is a direct measurement of a representative sample used to determine the viable organism concentration of a ballast water volume of interest. 21
PSC inspection Sampling inspection by PSC Position of sampling point(s) Alarm on any bypass line Ballast Water Management Plan approved by Administration Spare parts (e.g. chemical, UV lamp) Crew s familiarization for BWMS operation IBWM Certificate Ballast Water Record Book D-1 Sampling / Salinity D-2 Analyses / Indicative D-2 Analyses / Detailed 22