Ballasting / deballasting guideline for bulk carriers
Seag oing bulk carriers when not carrying cargo or is lightly loaded, sufficient ballast must be carried to ensure that the ship’s stress, stability, draft, trim and propeller immersion is within permissible limits to guarantee the safe handling of the vessel in the prevailing or expected conditions. In meeting these parameters the vessel must comply, at least, with the requirements of the IMO, Class (especially appendix to Class Certificate) and Port State Authorities. In 1993 IMO adopted Resolution A.774 (18) “Guidelines for Preventing the Introduction of Unwanted Aquatic Organisms and Pathogens from Ships’ Ballast Water and Sediment Discharges”. Masters are to ensure compliance with them. Ballast operations must always be carried out within the capabilities of the vessel and its systems. Designated officer The Chief Officer is designated to carry out these procedures and maintain all records as required. The Master is to ensure the Chief Officer is familiar with the requirements of this section including IMO Guidelines. The Master must also ensure that all the crew members are given the instruction and are aware of the need for ballast water control procedures and the procedures being adopted on board.
Planning of the ballast operations Ballast operations are always to be planned in advance by the Chief Officer and entered in the Cargo Loading and Discharge Plan. The plan is to be approved by the Master prior to commencing the operation. Each vessel must produce a standard plan for a complete change of ballast. Records and reporting When taking on ballast waters, the date and time of commencement and completion of the ballast operation, ship’s position, salinity (specific gravity) and amount of ballast water taken onboard must be recorded in the ship’s Deck Log Book. A report in the format shown in the appendix to IMO Guidelines must be completed by the Master and made available to the Port State Authority on request. Analysis certificates, ballast reports and shore receipts must always be kept on board in a separate file. When the Port State Authority water ballast control requirements (e.g. exchange of ballast at sea) cannot be met during the voyage due to weather condition, operational impracticability, etc, the Master must report this fact to the Company and the prospective Port State Authority prior to entering its national waters
(economical zone), so that appropriate alternative action can be arranged. Controls applied by port state authorities The Master is to check in advance with the local agent, and the latest Port Guide, for any information on ballast water sediment discharge procedures, being applied by the State Authorities at an expected port of call. These procedures may include, but are not limited, the following control actions: • The non-release of ballast water; • Ballast water exchange and sediment removal at sea or in acceptable areas; • Ballast water management practices aimed at minimising the uptake of contaminated water in ballasting and deballasting operations; • Discharge of ballast water into shore-facilities. Failure to comply with national requirements may lead to unnecessary delays for the ship. In some cases penalties may be applied by Ports State Authorities. The vessel may be required to proceed to an approved location to carry out the necessary exchange, seal the ballast tanks against discharge in the Port State’s waters, pump the ballast water to shore reception facilities, or prove, by laboratory analysis, that the ballast water is acceptable. Loading of ballast water When loading ballast every effort is to be made to ensure only clean ballast is being taken onboard and the intake of sediment is minimised. Where practicable, vessels are to avoid taking on ballast water in shallow water areas or in the vicinity of dredging operations. Vessels must not ballast if at all practicable in areas where there is a known outbreak of water communicable diseases or where phytoplankton blooms are occurring. It is recognised however, that when vessels trade to river or estuary ports, intake of some silts and sediment is unavoidable. In such situations the amount of silt taken on board can often be substantially reduced by planning to ballast on the flood tide when the suspended silt levels are normally lower. Vessels taking on ballast in river or estuary waters or any other areas where the purity of the water is in doubt, including areas of probable contamination from chemicals, disease, pathogens etc. must follow the control procedures . When ballast has been loaded in silted or otherwise polluted water, the ballast is to be changed as soon as possible after leaving that port. It is also essential that this is carried out to prevent the build up of mud in ballast tanks which may reduce the vessels cargo lifting capacity. Whenever possible the initial filling of the ballast tanks should be run in from the sea by gravity, in preference to pumping it in. In general, ballast tanks are to be filled to 100% capacity, but not be overflowed.
Discharge of ballast water No ballast is to be discharged in the continental shelf, coastal or port waters where ballast water and sediment control measures are being applied by State Authorities, the ballast water and sediment control procedures have been followed, or acceptable alternatives have been adopted. The effectiveness of the vessels procedures may be verified by Port State Authorities taking samples of ballast water and/or sediments from the vessel, to test for the continued survival of unwanted aquatic organisms and pathogens. Such samples may also be taken from suction wells, chain lockers and other areas where sediment may accumulate. In certain cases discharge of ballast will not be permitted until analysis of such samples is completed. The Master is to ensure that relevant written authorisation is obtained from the Port Authority prior to discharging any ballast to coastal waters of any country that exercises ballast control measures. Shortly after commencement and during discharge of any ballast overboard the surface of the sea is to be checked frequently to guard against accidental pollution.
Safety precautions during ballasting / deballasting operation bulk carriers recommended guide
Risk
of pressing up ballast tanks In a cargo damage case a vessel found pressed up its ballast tanks in order to optimise trim and to satisfy mandatory stability criteria. The operation resulted in the unexpected flooding of a cargo hold causing extensive damage to the cargo. The bulk carrier was carrying out ballast exchange operations mid voyage and pressed up one set of double bottom ballast tanks. On arrival it was observed that one of her holds had significant water inside and considerable damage to bottom stow cargo. The vessel had opened up several manhole covers for routine inspection of her ballast tanks. After the incident it was noted that the high-level bilge alarms in the hold were not functioning. Careful investigation revealed poorly secured manhole covers are still a frequent cause of water ingress into holds, many, but not all, arising after drydocking where shore staff have not secured covers properly.
If double bottom manhole covers are removed for whatever purpose, it is recommended a note be made of where and when, this not only acts as an aide memoire but also helps in defending claims should water ingress occur. Good maintenance should also be in place, the manhole covers/gasket arrangement and like should be routinely checked, if not already included as part of the routine inspection/maintenance programme associated with the ship's ballast tanks. Hold
high-level bilge alarms should be tested on a regular basis, logged and defects, if any, rectified immediately. (Source :UK P&I |Club) Ship’s Safety When planning and carrying out operations with ballast water the following factors must be taken into account: • Shear Force and Bending Moment • Stability and Free Surface Effect • Slack Tanks • Torsion Loads • Draft and Trim of the Vessel • Pumping Limitations. Ballasting must always be carried out at a safe rate, determined by the vessels design. The Ship’s course and speed is to be properly set depending on the prevailing weather conditions. Sufficient personnel must be available to allow the safe monitoring of the operation. Personnel Safety If tank entry is required to affect the taking of samples, carrying out a ballast tank inspection, or for manually removing solid sediments, then all the safety precautions of the Enclosed Space Entry Permit must be complied with. Ballast Tank’s Venting System It is of paramount importance that all segregated and permanent ballast tank vents are properly set up and in good condition prior to any ballast operation. All vent closures that are capable of manual operation must be in the open position. The original design venting capability must be available at all times. The vents are to be further checked soon after starting the operation to confirm that the tanks are venting freely. Improperly set ballast vents can result in severe structural damage to the vessel. Vent screens are to be kept free from paint as this can seriously reduce their volumetric capacity. Great care is to be taken in conditions where icing is occurring. In certain circumstances screens on ballast tank vents can become blocked by icing. During ballast operations in such conditions, the responsible officer is to ensure that all precautions are adopted to ensure the free venting of ballast tanks, and that regular checks are made to ensure continuous free venting throughout the operation. Cathodic protection
Uncoated clean ballast tanks have a sacrificial zinc anode system fitted to protect the entire tank structure. If loading ballast into tanks fitted with cathodic protection in a freshwater river or estuary, it is important to change the ballast at sea as soon as is practical, in order to achieve the full effect of the cathodic protection system. Inspections Ballast tanks must be inspected on a twelve-monthly basis and a report on the condition of the tank sent to the Management Office . More frequent inspections may be carried out if the tanks are in poor condition or if work has been carried out within the tank. If it has been necessary to weld securing arrangements, such as pad eyes, onto the side plating of a cargo hold for the lashing of cargo, then the area behind the plating within the tank must be inspected and touched up with a suitable coating. Check items 1. proper, diligent and recorded ballast tank inspections must be carried out and form a part of the ship’s planned maintenance system 2. ballast tank inspections should form the basis of a dry-docking defect list 3. a proper system of inspections and checks must be carried out to assess the integrity of ballast tanks after hold cleaning and during the ballast voyage 4. bulk carrier inspections should include all parts and areas where water ballast can get into cargo holds: bilge systems, manhole covers, and tank top and bulkhead welds 5. proper guidance should be given to masters and officers with respect to cargo carriage and ballast water management 6. advice and training should be given that pumping ballast can cause extreme pressures on the tank structures and fittings such as manhole lids, even when tanks are fitted with classapproved air vents. Consider only gravitating water ballast so as to reduce pressure on the tanks and manhole lids 7. ship’s procedures should always include rigorous checks on the ship’s watertight integrity, including daily tank and bilge soundings, bilge alarm tests, checks on sounding pipe caps and inspections of spaces not often visited, including cofferdams and void spaces
Control of transportation of marine organisms -ballast water sediment removal guidelne
The most realistic and practical method for the control of transportation of marine organisms and to control sediments, is to exchange ballast water in deep ocean or open sea areas. This will limit the probability that fresh water or coastal species will be transferred in the ballast water. The responsibility for deciding on such action rests with the Master. The Master must contact the Port State Authority of
his next port via the agents and determine if special control actions are required. The exchange is to be conducted in water depths greater than 2000 metres, or in those cases where this is not possible, exchange of ballast water is to be made well clear of coastal and estuary influences. Draining of each tank is to be done until pump suction is lost. This will minimise the likelihood of residual organism survival. The tank is then to be flushed over the bottoms by refilling (if possible – by gravity) to approx. 0.5 metre depth, twice, each time followed by complete draining until pump suction is lost. The tank is then to be refilled. The effectiveness of this flushing can be increased if the vessel is on a course that causes the vessel to roll slightly, however, the vessel must not deviate greater than 15o from the intended voyage course during the time of flushing.
When heavy sedimentation is observed after visual inspection, then manual sediment removal may be undertaken. Tanks are to be inspected visually for sediment build up at least once every three months wherever practical, and sediment build up recorded on the tank condition report which is to be forwarded to the Company. Flow Through Exchanges When a vessel cannot conduct a complete ballast change, a “flow through” (through ballast tank vents) exchange of ballast water may be an acceptable alternative for some tanks, however, it has little effect on sediment control. Due to the risk of building up the pressure in ballast tanks, and the possibility of damage to vent heads, screens, etc. this procedure would require Administration (Classification) approval and must not be attempted without prior special considerations and authority of the Company. Modification of tank venting arrangements may be necessary to avoid damage to the vent heads and screens. Discharge of Ballast Water to Shore Reception Facilities The Master is to check if there are any requirements for shore based discharge of ballast through voyage orders, agents instructions, “Guide to Port Entry”, etc. If there is any doubt the relevant Management Office must be referred to for advice, before arrival. Manual removal of solid elements Care is to be taken when manually removing sediments while the ship is in port or in continental shelf waters, to ensure sediments are not discharged into these waters. Sediments must be disposed of ashore and processed according to the
local requirements. A log book entry is to be made and receipts obtained. This part applies to solid sediment discharges, and does not affect sediments that can be removed from the chain locker or wells by hand hosing. Sample analysis certificate Vessels may avoid ballast changing in some circumstances by having their ballast water or harbour source samples analysed by a laboratory at the departure port. Where the analysis shows the ballast or sediment to be free from unwanted aquatic organisms or pathogens an analysis certificate is to be provided by the Master to the Port State of arrival. This must be carried out by fax several days prior to arrival in case the analysis is rejected, in order that the ballast change procedures can be applied prior to arrival.
Risk of Partially filled ballast holds or tanks of a seagoing bulk carrier
Saili ng with partially filled ballast holds is prohibited unless the approved loading manual approves of such a practice. Cargo holds designed for partially filled in harbour for the purpose of reducing the ship's air draught are not to contain any water ballast while at sea. Where ballast holds, and in some instances ballast tanks, are partially filled, there is the likelihood of sloshing. Sloshing is the violent movement of the fluid's surface in partially filled tanks or holds resulting from the motion of the ship in a seaway. Sloshing will result in the magnification of dynamic internal pressures acting on the hold/tank boundaries. For any tank design, dimensions, internal stiffening and filling level, a natural period (frequency) of the fluid exists, which, if excited by the ship's motions, can result in very high pressure magnification (resonance) which can result in damage to the tank/hold's internal structure. To minimise the effects of sloshing, the liquid's motion needs to be controlled by ensuring that tanks are either pressed up or empty (sloshing can occur at low filling levels). Where a ship has been specially designed for partially filled ballast tanks and/or hold(s) whilst at sea, the filling levels specified in the ship's loading manual are to be followed.
Designated Ballast Hold When using the vessel's ballast hold for long sea passages in ballast condition, the operation of ballasting or deballasting is to be supervised directly by the Chief Officer, the Master being responsible for ensuring that this operation is carried out in the correct manner. The Master is never to put to sea with this hold partly filled, and the ballasting operation must be completed before proceeding.
Charterers and Owners must be informed well beforehand of the time required to complete this, and if necessary, arrangements will be made for the vessel to proceed to a safe anchorage for this purpose. Similarly, the Master should not commence deballasting of the hold until the vessel has arrived at a safe anchorage. Under extenuating circumstances, permission may be requested from the management office to deballast the hold at another location subject to a full risk assessment having been completed. Before commencing the ballasting/deballasting operation, all extra ballast vents must be fully opened and checked by the Chief Officer, to facilitate the entry/exit of increased airflow due to the large volume of water involved. Ideally, and if weather permits, the main hatch cover is to be opened as this will remove any doubt as to the adequacy of air entry/exits facilities and permit better observation of progress. It is the Officer on watch’s responsibility to ensure that the hold ballast line is blanked off properly in the hold, thus avoiding any risk of accidental entry of water into cargo hold after loading. The Chief Officer is to personally to check this, and report to the Master.
Bulk cement - Preparations, loading, carrying & handling precautions
In the most general sense of the word, cement is a binder, a substance that sets and hardens independently, and can bind other materials together. The word "cement" traces to the Romans, who used the term opus caementicium to describe masonry resembling modern concrete that was made from crushed rock with burnt lime as binder. The volcanic ash and pulverized brick additives that were added to the burnt lime to obtain a hydraulic binder were later referred to as cementum, cimentum, cäment and cement. Cement used in construction is characterized as hydraulic or non-hydraulic. Hydraulic cements (e.g., Portland cement) harden because of hydration chemical reactions that occur independently of the mixture's water content; they can harden even underwater or when constantly exposed to wet weather. The chemical reaction that results when the anhydrous cement powder is mixed with water produces hydrates that are not water-soluble. Non-hydraulic cements (e.g., lime and gypsum plaster) must be kept dry in order to retain their strength.
Concrete should not be confused with cement because the term cement refers to the material used to bind the aggregate materials of concrete. Concrete is a combination of a cement and aggregate. Cement is a finely ground powder which becomes almost fluid in nature when aerated or significantly disturbed, thereby creating a very minimal angle of repose. After loading is completed, de-aeration occurs almost immediately and the product settles into a stable mass. Cement dust can be a major concern during loading and discharge if vessel is not specially designed as a cement carrier or shore
equipment is not fitted with special dust control. Hazard :It may sift when aerated. This cargo is non-combustible or has a low fire risk. Stowage & segregation : No special requirement. Hold cleanliness : Clean and dry as relevant to the hazards of the cargo . Ventilation : Shall not be ventilate during voyage. Loading The ship shall be kept upright during loading of this cargo. This cargo shall be so trimmed to the boundaries of the cargo space that the angle of the surface of the cargo with horizontal plane does not exceed 25 deg. Both the specific gravity and the flow characteristics of this cargo are dependent on the volume of air in the cargo. The volume of air in this cargo may be up to 12 %. This cargo show fluid state prior to settlement. The ship carrying this cargo shall not depart until the cargo settled. After the settlement, shifting of the cargo is not liable to occur unless the angle of the surface with the horizontal plane excesses 30 deg. This cargo shall be kept as dry as practicable. This cargo shall not be handled during precipitation. During handling of this cargo, all non working hatches of the cargo spaces into which the cargo is loaded or to be loaded shall be closed Precautions Appropriate precautions shall be taken to protect machinery and accommodation spaces from the dust of the cargo. Bilge wells of the cargo spaces shall be protected from ingress of the cargo. Person who may be exposed the dust of the cargo shall wear protective clothing, goggles or other equivalent dust eye protection and dust filter masks, as necessary. Bilge wells shall be clean, dry and covered as appropriate, to prevent ingress of the cargo. Carriage After completion of loading of this cargo, the hatches of the cargo spaces shall be sealed as necessary. All vents and access ways to the cargo spaces shall shut during the voyage. Bilges in the cargo spaces carrying this cargo shall not be pumped unless special precautions are taken. Discharge No special requirement Clean up In the case that the residues of this cargo are to be washed out, the cargo spaces and the other structures and equipment which may have been in contact with this cargo or its dust shall be thoroughly swept prior to washing out. Particular
attention shall be paid to bilge wells and framework in the cargo spaces. The fixed bilge pumps shall not be used to pump the cargo spaces, because this cargo may make the bilge system inoperative. Example Loading port: – Kanda - Japan Discharging port :-Kwinana-Australia Facing problems A wide variety of problems can exist when carrying cement. When vessels have sailed around the Cape, the cement cargo stored underneath other cargoes is often damaged in the bad weather as it has not been adequately protected or packed. Cement cargoes also run the risk of becoming caked due to water ingress. One of the major causes of cargo damage in some ports is due to improper handling of the cargo by stevedores; this results in torn cement bags spilling cargo in the hold. Problems often occur due to mismanagement of the cranes and machinery, meaning bags are dropped, which could be very dangerous and can result in cargo being lost over the side. Additionally, theft is a noticeable problem and reminded to remain vigilant. Things to do 1. masters should confirm that weather routing advice takes account of the water-sensitive nature of the cargo carried. Masters should let it be known when they have reservations 2. stevedores and charterers should be approached when incorrect loading equipment is used 3. before loading cement or other dusty cargoes, the coaming drain holes should be taped over to prevent the entry of dust. Tape should be removed before blowing down 4. after a closed loading operation, the trackways should be cleaned if possible and cleared to free the drain holes, (if the weather allows). Masters should advise their owners and charterers of this requirement
Checklist to show stability, hull strength, draft, trim, suitability of cargo for a bulk carrier The conditions of stability, hull strength, draft and trim of bulk carriers at sea and on arrival / departure at / from port and during loading / unloading cargo, bunkering and water ballast exchange, should be worked out, ensuring safety of the vessel. Safety of the cargo vessel depends on proper GM, stress calculation and other factors as being within appropriate Limits. Following are the check item confirming stability and hull strength of cargo ship:
1. The GM value within acceptable limits as specified in the loading manual and in compliance with IMO rules upto arrival next port? 2. GZ curves of the vessel to be fully understood, and their characteristics confirmed 3. Expected weather and sea conditions, to be taken into consideration when confirming stability & hull strength 4. Free surface effects and any sloshing effects for the planned passage to be taken into consideration. 5. Any restrictions specified in the loading manual to be taken into consideration. 6. Values of bending moments, shearing forces and torsional stresses at sea to be within acceptable limits upto arrival next port. 7. The sailing draft to be within applicable loadline or port/passage limits/restrictions. 8. Air draft limitations due to bridges, cargo handling equipment or other obstructions to be assessed as necessary. 9. The cargo density in accordance with maximum permissible values and precautions as per the loading manual to be followed. 10. Forward draft limit (per loading manual) to prevent slamming to be confirmed. 11. Propeller immersion ratio to be assured. 12. Trim and draft changes during voyage in fresh or brackish water such as rivers, canals and lakes, to be taken into consideration. 13. Squat due to shallow water effect to be taken into consideration. 14. Safe under keel clearance to be assured . 15. Fuel oil and fresh water consumptions to be taken into consideration.
Check items Following are the guideline to check suitability of loading/ unloading solid bulk cargo i) Cargo holds and hatch openings are suitable for cargo operations ii) Holds are clearly numbered on hatch covers/ coamings
iii) Hatch covers, hatch operating systems and safety devices are in good operational condition iv) List indication lights, if fitted, have been tested prior to arrival and are operational v) If applicable, loading instrument is certified and operational vi) Propulsion/auxiliary machinery is in good operational order vii) Mooring equipment is in good functional order
Planning and control of cargo loading and unloading operations for Bulk Carriers
Prep aring vessel for cargo operations -Collecting cargo and Port Information The safe operation of bulk carriers is dependant on not exceeding allowable stresses in the cycle of loading, discharging, ballasting and de-ballasting. To prepare the vessel for cargo stowage and a safe planning, the loading and unloading sequences and other operational matters should be informed well in advance. The shore terminal should provide the ship with the following information : i) Prior to loading bulk cargo , the shipper should declare characteristics & density of the cargo, stowage factor, angle of repose, amounts and special properties. ii) Cargo availability and any special requirements for the sequencing of cargo operations. iii) Characteristics of the loading or unloading equipment including number of loaders and unloaders to be used, their ranges of movement, and the terminal's nominal and maximum loading and unloading rates, where applicable.
iv) Minimum depth of water alongside the berth and in the fairway channels. v) Water density at the berth. vi) Air draught restrictions at the berth. vii) Maximum sailing draught and minimum draught for safe manoeuvring permitted by the port authority. viii) The amount of cargo remaining on the conveyor belt which will be loaded onboard the ship after a cargo stoppage signal has been given by the ship.
ix) Terminal requirements/procedures for shifting ship. x) Local port restrictions, for example, bunkering and deballasting requirements etc. Cargo trimming is a mandatory requirement for some cargoes, especially where there is a risk of the cargo shifting or where liquefaction could take place. It is recommended the cargo in all holds be trimmed in an attempt to minimise the risk of cargo shift. The ship's Master should be aware of the harmful effects of corrosive and high temperature cargoes and any special cargo transportation requirements. Ship Masters, deck officers, charterers and stevedores should be familiar with the relevant IMO Codes (for example, the IMO Code of Safe Practice for Solid Bulk Cargoes, the IMO Code of Practice for the Safe Loading and Unloading of Dry Bulk Carriers and the SOLAS Convention). Devising a Cargo Stowage Plan and Loading/Unloading Plan Exceeding the permissible limits specified in the ship's approved loading manual will lead to over-stressing of the ship's structure and may result in catastrophic failure of the hull structure. The amount and type of cargo to be transported and the intended voyage will dictate the proposed departure cargo and/or ballast stowage plan. The officer in charge should always refer to the loading manual to ascertain an appropriate cargo load distribution, satisfying the imposed limits on structural loading. There are two stages in the development of a safe plan for cargo loading or unloading: a) Step 1: Given the intended voyage, the amount of cargo and/or water ballast to be carried and imposed structural and operational limits, devise a safe departure condition, known as the stowage plan. b) Step 2: Given the arrival condition of the ship and knowing the departure condition (stowage plan) to be attained, devise a safe loading or unloading plan that satisfies the imposed structural and operational limits. In the event that the cargo needs to be distributed differently from that described in the ship's loading manual, stress and displacement calculations are always to be carried out to ascertain, for any part of the intended voyage, that: a) The still water shear forces and bending moments along the ship's length are within the permissible Seagoing limits. b) If applicable, the weight of cargo in each hold, and, when block loading is adopted, the weights of cargo in two successive holds are within the allowable Seagoing limits for the draught of the ship. These weights include the amount of water ballast carried in the hopper and double bottom tanks in way of the hold(s). c) The load limit on the tanktop and other relevant limits, if applicable, on local loading are not exceeded.
The consumption of ship's bunkers during the voyage should be taken into account when carrying out these stress and displacement calculations. Whilst deriving a plan for cargo operations, the officer in charge must consider the ballasting operation to ensure: a) Correct synchronisation with the cargo operation. b) That the deballasting/ballasting rate is specially considered against the loading rate and the imposed structural and operational limits. c) That ballasting and deballasting of each pair of symmetrical port and starboard tanks is carried out simultaneously. During the planning stage of cargo operations, stress and displacement calculations should be carried out at incremental steps commensurate with the number of pours and loading sequence of the proposed operation to ensure that: 1) The SWSF and SWBM along the ship's length are within the permissible Harbour limits. 2) If applicable, the weight of cargo in each hold, and, when block loading is adopted, the weights of cargo in two adjacent holds are within the allowable Harbour limits for the draught of the ship. These weights include the amount of water ballast carried in the hopper and double bottom tanks in way of the hold(s). 3) The load limit on the tanktop and other relevant limits, if applicable, on local loading are not exceeded. 4) At the final departure condition, the SWSF and SWBM along the ship's length are within the permissible Seagoing stress limits. During the derivation of the cargo stowage, and the loading or unloading plan, it is recommended that the hull stress levels be kept below the permissible limits by the greatest possible margin. A cargo loading/unloading plan should be laid out in such a way that for each step of the cargo operation there is a clear indication of:i) The quantity of cargo and the corresponding hold number(s) to be loaded/unloaded. ii) The amount of water ballast and the corresponding tank/hold number(s) to be discharged/loaded. iii) The ship's draughts and trim at the completion of each step in the cargo operation. iv) The calculated value of the still water shear forces and bending moments at the completion of each step in the cargo operation. v) Estimated time for completion of each step in the cargo operation.
vi) Assumed rate(s) of loading and unloading equipment. vii) Assumed ballasting rate(s) The loading/unloading plan should indicate any allowances for cargo stoppage (which may be necessary to allow the ship to deballast when the loading rate is high), shifting ship, bunkering, draught checks and cargo trimming. The loading or unloading plan should only be changed when a revised plan has been prepared, accepted and signed by both parties. Loading plans should be kept by the ship and terminal for a period of six months. A copy of the agreed loading or unloading plan and any subsequent amendments to it should be lodged with the appropriate authority of the port State. Operational guidance All bulk carrier officers should have clear guidance and instructions available onboard their ship. There should be guidance on: • preparation of holds • carriage requirements of bulk cargo • safety aspects of bulk cargo carriage etc (liquefaction, heating, hazardous gases, oxygen depletion, entry into enclosed spaces)
Operation of self- unloading bulk carriers -The conveyor system, gravity free-flow concept & SUL terminology
Self unloading bulk carriers originated in the Great Lakes. The ‘Conveyor System’ was installed into the Lakers size bulk carriers to deliver to ports with limited or no bulk-handling facility. These vessels transported material between the ports of the St. Lawrence Seaway and the Great Lakes; thus serving as an inland extension to the major ocean routes from Canada. With a lack of bulk-handling facilities in many ports of the world this application was introduced into the deep-sea trades. This was done by strengthening the existing SUL Lakers, converting the ordinary bulk carriers of Handy and Panamax sizes, and recently building new state-of-the-art self-unloading bulk carriers. The conveyor system The ‘Conveyor System’ is the main distinguishing feature of the vessel. An essentially industrial type conveyor system and structure, designed for shipboard use, has given a specific identity to this type of bulk carrier generally called ‘SelfUnloaders’.
In this design the ship holds terminate above the DB tank top forming a series of numerous open conical shapes called ‘hoppers’. These hopper openings are capped by hinged or sluice ‘gates’, which are operated hydraulically.
Fig:Self unloader on passage The void space formed between the underside of these hoppers and the DB tank top along the length of the ship is called the ‘tunnel’.The conveyor belt runs in the tunnel along the ships length, and is fed by cargo through the ‘gates’.Gravity is utilised and the flow of cargo is controlled; governed by the load on the belt. The cargo is then lifted up vertically (loop or elevator lifts) or by gradual inclines and is transferred to the ships boom.
Fig: Self unloader components in operation The boom is an extended structure with freedom of direction situated on the main deck, and encases the boom belt, for conveying the cargo to the shore terminal. The concept of "gravity free-flow" The ‘Concept of Gravity Free-Flow’ is utilising the weight of the solid bulk cargoes to slide down through the gates onto the hold conveyor belt. The conveyors work as mechanical extensions, which transport the cargo horizontally and vertically. Some cargoes do not flow as well as others; and the sloping sides of the cargo holds are lined with UHMW sheeting, to encourage cargo flow, however on occasion certain cargoes may require to be assisted normally. The SUL Bulk Carriers are not dependent on bulk-handling infrastructure on shore. The ships boom conveyor is able to discharge cargo to the shore i.e. it is the final stage in the transfer of the cargo leaving the ship and it can be positioned to discharge the cargo in most positions to a quay, to the ground, hopper, barge or other ship etc. The SUL ‘Straight Boom’ has freedom of movement in three directions up to the ships beam, and the ‘Articulated Boom’ also aft of the beam. Some modifications
to the boom (‘Short Boom’) can be made to make it more flexible in nature. The ‘Shuttle Boom’ has its limitations, and is used mainly for hopper discharge. Self-Unloader technology Many self-unloaders operate with a mix of high-tech and simple gravity. The cargo falls through controlled hydraulic gates onto conveyor belts located beneath the holds. The belts carry the cargo toward the stern of the ship where it’s transferred to an elevating system and lifted toward deck level. Once there, it is released onto the discharge boom, which is slewed to either port or starboard - up to 65 metres from the side of the ship, and then is off-loaded to the shore, either directly onto a stockpile or into a receiving facility. The Hybrid Self-unloading vessels discharge using a mechanism, mostly cranes. They lift the cargo and discharge into hoppers on the deck. A series of conveyors mounted on the deck carry the cargo to the discharge boom, where the cargo is ultimately discharged to a single point on shore. Deep sea self-unloading bulk carrier terminology •
Backstop : ratchet assembly, which allows a shaft to turn in one direction only.
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Beater wheel :(pocket elevator) positioned at the top of the system to assist in emptying of cargo from pockets.
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Belts :conveyors.
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Belt-Life :belt lifespan.
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Belt Scales :instruments used to measure cargo flow rate.
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Boom Structure : supporting conveyor belt, which discharges cargo to shore.
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Boom hub :pivot point of boom.
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Bucket elevator :belt belt with attached components forming buckets or pockets.
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Carriage wheels :wheels attached to belt tensioning carriage.
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Chute :steel structure, which directs cargo from one belt to another.
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Clips : products used for temporary repair of conveyors.
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Cold repair :repair carried out using rubber compound on surface of belt.
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Collomatic winch : hydraulic mooring winches in use, where applicable.
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Coupling grid :steel component used in Falk couplings as connection piece between the coupling halves.
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Crocodile clip :type of belt clip used on boom belt (where fitted) to shorten the boom belt when required for a ‘Short Boom’ discharge.
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Cross-Conveyor :another term for a transfer conveyor.
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Deflector plate :steel assembly placed inside hoppers to direct fall of cargo from one belt to another.
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Deflection Pulley :a pulley which alters the alignment of the belt.
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Deflection wheel : (pocket elevator) type of pulley used on pocket elevator as a bend pulley. Dipping :unloading of a certain number of gates in a cargo hold in the early stages of a discharge.
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Discharge rate :flow rate of cargo during discharge.
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Draft gauges :remote instruments used to measure and display the drafts of a vessel.
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Draining :another term for “clean out” this is the latter stage of a discharge following “dipping” and “main discharge”, when all gates are unloaded.
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Drive pulley :a lagged pulley which is driven by a drivetrain, this pulley transmits the driving force to the belt.
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Emergency stop :switch providing the facility to shutdown the conveyor system when activated. These are placed at convenient locations on the ships main deck, at hatch coamings, in cargo control rooms at loop and in tunnel. These are also activated by pull-chords (see below).
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Falk coupling :a type of flexible coupling used on the drive pulleys.
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Flexco hinged fastener :a belt clip used in temporary belt repairs.
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Fluid drive :a coupling which is used to limit motor starting current.
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Gordon Scraper :trade name for the type of urethane belt cleaners in use on CSL vessels.
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Gooseneck hoppers : hopper located at the top of the elevator belts.
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Guide rolls : rollers to protect the belt from damaging itself against steel work or other abrasive surfaces; they do not touch the edge of the belt when running normally.
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Hang-ups :stacks of cargo which have not fallen through the gates as intended.
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Dead pulley :pulley situated at the discharge end of a conveyor belt.
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Hold conveyor belt :another term for tunnel belt.
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Hopper : a steel structure which contains and directs the flow of cargo from one belt to the next.
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Hog Back :inverted “vee” steel structure in cargo hold. Hot repair :vulcanisation. Hub :drive pulley. Idlers :rollers.
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Impact Idlers :lagged runner rollers usually located beneath a hopper.
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Impact plate :deflector plate or plate which absorbs force of cargo being discharged from a belt.
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Listometer lights :a set of five lights, two red, one white and two green which are controlled by a mercury switch. The white light, which is located in the centre of the set, illuminates when the vessel is upright. If the vessel takes a list of ½ degree, the inner red or green light will illuminate and the white light will be extinguished. If the vessel takes a further ½ degree list the second red or green light will illuminate. Red lights will indicate a list to port while green lights indicate a list to stbd.
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Load rate :rate at which cargo is loaded into the vessel.
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Loadicator :instrument which is used to calculate a load (or unload) plan for a vessel which will maintain the hull structure within safe stress limits.
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Loop belt : a type of elevator belt employing two belts which rotate in opposite directions.
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Lower bend pulley :bend pulley situated in the lower section of an elevator belt system whose function is to change the attitude of the belt.
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N.C.Feeder :non-consolidated system which uses a reciprocating motion and a series of openings to bring cargo down from a cargo hold onto a tunnel belt.
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Parking bolster : a support bracket attached to a boom at the designated point at which the boom can be safely supported whilst the vessel is at sea.
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Parking saddle :the support structure attached to the main deck onto which the parking bolster can be landed when the boom is stowed for sea.
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Pillow block :a bearing complete with mounting which has securing bolt holes cast into its base.
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Plough scraper :a scraper which is placed onto the return strand of a conveyor belt whose purpose is to deflect cargo material which may have fallen onto the return strand of the belt (usually vee formed). Pocket elevator belt a type of elevator belt which is fitted with cleats and side walls.
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Pull-chord :A length of small diameter wire (3 to 5 mm) which is strung along the sides of a conveyor belt. The lengths of wire are connected to switches, which stop the conveyor immediately in case of emergency. The number of switches depends upon the length of a conveyor belt. The switch has to be physically reset before the belt can again be restarted. Pull chord switches must be pulled before any maintenance work is carried out on a belt.
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Reducer : reduction gear box.
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Return idler :roller mounted beneath the return strand of a belt.
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Return roller :same as above.
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Rubber covered disc type idlers :reduce the impact of cargo being loaded onto the belt. The impact of cargo being loaded onto the belt is often the cause of severe cuts and gouges.
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Rubber lagging :is recommended for pulleys, to improve the co-efficient of friction, reduce slippage, and increase life of the pulley and belt. Grooving of the lagging has a cleaning effect on the belt, and breaks the film if moisture is present on the belt, to avoid slippage. The methods of fitting lagging onto pulleys varies, but vulcanising is generally used for shipboard pulleys.
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Saddle-piece :a piece of conveyor belt of usually 4 metres in length which can be used as an insert in the event of belt damage. Saddle-back inverted “vee” structure running fore and aft in a cargo hold, which acts as a flow divider between the gates to the tunnel belts.
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Scoop arm :a weighted lever, which is attached to the scoop of a Fluidrive coupling.
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Scraper :belt cleaner.
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Scraper bracket; :bracket supporting a belt cleaner.
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Scraper blades :hard wearing material which is in constant contact with a belt, used for removing material from a belt.
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Skirts :guides mounted at each side of a belt, which prevent cargo from being ejected.
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Skirt boards :are used in hoppers and chutes to guide/centre and settle the load on the belt as it leaves the point of loading. Their length is usually not less that 4 or 5 times the belt width.
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Snub :a pulley or an idler which is mounted close to a drive pulley, causes the belt to have increased circumferential contact with the drive pulley lagging.
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Speed switches :switched which detect a significant fall in belt speed whose function is to shut down the upstream belt to prevent a blockage of the system in the event of a belt stopping. or slowing down.
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Spillage :cargo which has spilled from the belts and remains on board on departure from an unloading port.
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Splice :the area at which a conveyor belt is bonded.
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Stub idler :an idler or roller, which is short in length and is mounted on a side bracket.
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Tail pulley drive :a tail pulley which is connected to drive trains.
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Tail pulley :large diameter pulley situated at the non-discharging end of a conveyor belt.
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Take-away rate :the rate (capacity) of a shore conveyor system.
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Take-up unit :hydraulic power pack for belt tensioning.
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Take-up sheaves :sheaves on the take-up unit, which allows adjustment of alignment.
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Take-up pulley :pulley on the take-up unit.
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Tank gauges : remote gauges displaying ballast tank surroundings.
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Tension (belt) belt :tensions to be set and maintained according to manufacturer’s instructions for optimum conveyor operations.
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Teledyne valve : hydraulic flow control valve used on gate controls to open or close a gate.
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Training the belt :effectively guiding the conveyor belt to run along the centreline by proper adjustment of carrying components and tensioning.
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Transfer belt :athwartship running belts used to change the direction of cargo travel and to feed the hopper for the elevating belt.
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Trash pump :centrifugal pump situated on the tunnel bilge used to pump out residues and slurry.
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Traffic lights :lights-red, amber and green in a vertical line, placed at frequent intervals along the side of hold conveyor belt. These lights indicate the load on the hold conveyor belt they serve. ‘Red’-overload. ‘Amber’optimum load. ‘Green’-under capacity. The limits of the load are set on the cargo control panel in the CCR.
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Troughing idlers :used on the ‘loop’ elevating system, to guide the edges of the sandwiched belts upwards and act as a seal.
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Tunnel : the fore and after space between the DB tank tops and the hold bottom hoppers, in which the hold conveyors run.
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Unbranded hot splice : vulcanised splice.
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Under-carriage : the carrying components of a conveyor belt e.g. rollers, frames etc.
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UHMW :the special low friction plastic lining attached on the sloping hopper sides in cargo holds to enhance cargo flow and prevent hang-ups. These are a series of sheets attached to the metal surface by studs and caps.
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Vibrator: a rotary unit containing hydraulically driven eccentric mechanism that creates vibrations and resonance. They are mounted on stiffeners on the hopper-sides in the tunnel, and at pre-determined intervals. They are used for bringing down cargo hang-ups, and the efficient cleaning out of gates.
Self- unloading bulk carriers operation -Safe working practices & environment protection Operation of self -unloading bulk carriers involved numerous hazards and careful considerations are important during all aspect of shipboard activities. Following are some basic guidance for safe working practices onboard and environment protection. 1. 2. 3. 4. 5. 6. 7.
Read the instruction manuals prior bulk cargo handling Make sure all guards are in place before start-up Isolate/lockout power before commencing any maintenance work Avoid contact with any moving parts Beware of ‘pinch points’ where the conveyor belt runs into a pulley. Keep loose sleeves, gloves, cleaning rags away from moving parts. Provide guard rails, or methods of protection while working near running conveyors. 8. Do not exceed design loads or service condition. 9. Do not modify equipment without proper authorisation. 10. Do not remove protective shields, guards, covers or any warning signs. 11. Wire rope clips on take-up assemblies must be checked and retightened after training the belt.
12. The safety cables are to prevent the pulley assembly from falling if the belt breaks, these should be checked regularly. 13. Never use hands to check for hydraulic leaks. 14. Do not step on coupling guards or protective covering. 15. Do not try to remove a fallen object on the running belt, pull the ‘pull chord’ if required. 16. Do not cross over or under conveyor belts and machinery, use the catwalks or walkways provided. 17. Do not reset ‘emergency switches’ without verifying the reason for them being activated.
18. Do not enter the Loop area without authorisation, be cautious of any falling cargo, and remember that dusty cargo will impair your visibility. 19. Persons making rounds of the SUL system are required to inform the CCR their whereabouts. 20. All personnel are to know the position of all ‘emergency stops’ and ‘pull chords’. 21. All walkways must be clear of obstructions. 22. All wiring must be insulated and clamped in position. 23. Portable lights if required to use must be guarded and intrinsically safe. 24. All tunnel lighting must be covered and intrinsically safe. 25. Protect the conveyor belts adequately before carrying out hot-work in the vicinity.
Fig:self unloader BUFFALO 26. Hydraulic oil will flash on introduction of heat and start a fire, especially hydraulic oil spread on water. 27. All light and sound signals must be understood by all. 28. All communications must be relevant and clear. 29. All electrical switchboards must be protected from dust, especially coal and grain dust which is inflammable. Protective Clothing Protective clothing as appropriate must be worn at all times during cargo operations as follows: • Safety helmet with strap. • Steel toe safety shoes. • Leather working gloves • Working coverall. • Clear safety goggles. • Dust mask. • Safety torch. • Carry strap and protective cover for walkie-talkie set. Safety Measures Incorporated in the System
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Audio Visual alarms:Red Light – indicates shut down Yellow Light – indicates alarm ‘O’ speed shut down for motors: - indicates if there is pulley slippage relative to the left speed. This avoids friction damage to the underside of the belt.
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Tunnel lights:Indicates the load as follows: Red light - overload Amber - correct Load Green - low load The ‘emergency stops’ and ‘pull cords’:- These switches when activated, stop the system sequentially. They are to be activated in an emergency situation, or when personnel are working on the system. Transfer hopper pressure switches:These switches are activated by a build up in pressure due to clogging in a transfer hopper, and stop the hold conveyor. The Listometer lights:- These lights are fitted on the foremost and loop-line. They indicate the vessels list as follows:1. Port List - 1 Red = ½ degree 2. Port List - 2 Red = 1 degree 3. Port List - 2 Red Flashing = more than 1 ½ degrees 4. Starboard List - 1 Green = ½ degree 5. Starboard List - 2 Green = 1 degree 6. Starboard List - 2 Green Flashing = more than 1 ½ degrees
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Maintaining the vessel in an upright condition is critical, and lists in excess of 1 degree must be corrected. Lists of more than 1 degree can lead to the following problems:1. Faults in the tracking of the belts 2. The boom slewing system hydraulics may exceed the design pressures, and the relief valves will lift, stopping the boom. There are no heat or smoke sensing systems in the loop-tunnel, and regular fire watches must be arranged especially during repairs. These watches must be carried out at least two to six hours, following completion of any hot work in the loop and tunnel areas. Note that there are no heat or smoke sensors in the Loop-Tunnel, and therefore frequent fire rounds have to be made by the persons assigned, especially when the system is in operation, and when carrying out repairs. Fire rounds are to be taken at least two and six hours after completion of any hot-work in the Loop and Tunnel areas. Precautions when Bunkering During Loading/Discharging: Notices must be posted and warnings issued to all concerned to the effect that bunker hoses are connected.
Alterations in draft and trim due to bunkering must be closely monitored, to ensure that an adequate depth of water at the berth is maintained, and that excessive trim which would adversely affect the boom and conveyor belts, is avoided. Cargo operations During cargo operations, gangways should be periodically inspected for cleanliness, tightness of handrail lines, deployment angle, safety net placement, and distance of the bottom step plate from the wharf. Any dangerous conditions on the gangway should be corrected. It is good practice to keep a log at the top of the gangway, so that the longshoremen can sign on when they board the ship and sign off when they leave. The log also serves a practical purpose, as it enables the crew to check who is on board and to ensure that all of the longshoremen have left the ship when cargo operations are completed. The main deck should be inspected at regular intervals (including areas where longshoremen are or will be working and also access routes to these areas) to make sure that there is no oil, grease or any foreign substance on deck. Any open manhole covers should be closed or properly guarded and guards or cautionary signs should be placed around any obstructions on deck that may present a trip hazard. Crewmembers should ensure that any ship equipment or areas under their active control during cargo operations do not pose a danger to the longshoremen working near the equipment or passing through the area controlled by them. Crew should also make deck log entries of the periodic inspections of the gangway and main deck confirming they are clean and in good working condition. They should also note the time of any cleaning/maintenance on the gangway or main deck, specifying the area cleaned.
Versatile self-unloading systems for cement carriers Marine Selfunloaders
Decades of experience in dry bulk handling for cement carriers The renowned MacGregor brand signifies advanced and well-proven cement handling systems to cargo owners and shipping companies throughout the world. Its reputation has been strengthened since 1947, when the first totally-enclosed selfloading/unloading cement carrier, with highly-automated cargo-handling gear, was delivered. Over the past 60 years, MacGregor cement handling systems have been installed in over 100 cement carriers sized between 500 and 40,000 dwt; most of these are still in operation.
Applications The well-proven MacGregor cement handling system comprises a range of conveyors, both mechanical and pneumatic, which can be combined to deliver the required function and cargo handling rates. Easily adaptable to any size and shape of vessel, the system is suitable for newbuildings as well as conversions. Overall, the system ensures the reliable and highly-efficient seaborne transportation of cement from producers to consumers all over the world. It is designed for use with range of different receiving systems and is therefore able to load and unload in many different terminals. The continual development of MacGregor systems and sustained efforts to create new customised solutions, enable Cargotec to maintain its status as a worldleading supplier of cement handling systems for selfunloading ships.
Dust-free material handling
MacGregor shipboard solutions for cement carriers are designed with a unique screw conveyor technology, which incorporates a totally-enclosed conveying line for environmentally-friendly operation in all weather conditions.
Low power consumption MacGregor screw-conveyor technology ensures the lowest possible power consumption, saving both money and reducing emissions due to a reduced need for power generation.
View of a state-of-the-art cement carrier equipped with a MacGregor self-unloading system: aeration panels, screw conveyors and a blow pump for mechanical and pneumatic loading/unloading
Main system components of a MacGregor cement self-unloading solution Screw conveyors
MacGregor vertical and horizontal screw conveyors are used to distribute cement to and from holds to discharge facilities on shore. This process is done at a high rates with the lowest possible energy consumption.
Fluidised bottoms Fluidised bottoms are used for reclaiming cement in each hold. A special long-life aeration fabric ensures negligible residue in the holds after unloading is complete.
Blow pumps
Blow pumps are used for pneumatic conveying from ship to silo. MacGregor pneumatic systems are constantly being refined at our full-scale test plant. This is to ensure that they achieve the highest possible efficiency rates, which can be applied either for reducing power consumption, increasing capacity or for conveying over greater distances.
Bulk discharge boom Bulk discharge booms are used for mechanical unloading from ship to shore. Screw conveyor technology enables a totally-enclosed operation with no dust emissions to the surrounding environment. The boom can also be adapted for loading directly to road tankers.
Electrical control system
Electrical control systems are used to maximise efficiency during the automatic control and supervision of different loading/unloading operations. The loading and unloading operation is fully-controlled by one person in the control room.
Key benefits • well-proven technology • high-handling capacities • designed for newbuildings and conversions • flexible system with future add-ons and upgrades available • fully automatic loading and unolading operation • low operational costs • environmentally friendly • system compliance with latest IMO rules • ease of maintenance
Versatile in every aspect When adopting a MacGregor concept, we can offer cement-handling systems with great flexibility. This prepares ship owners for the future, as vessels are able to perform at high capacity rates in virtually any existing port set-up and those not yet built. The system’s modular concept allows for easy tailoring of cargo handling components to fulfil every specific demand that arises.
Newbuildings for the future Designs allow for future system add-ons and upgrades to be undertaken without major modifications to the original solution. The benefits and cost savings are substantial if the system needs to be upgraded in the future.
Existing system upgrades and modifications
In many cases, existing cement carriers can be modified to perform with receiving systems other than those that it was originally designed for. Consequently, we offer upgrades and enhancements to owners of older cement carriers. Our expertise in cement handling can then be used by ship owners who have cement carriers that are already in operation, but in need of adjustments or upgrades.
1 H W CARLSEN UNLOADING SYSTEMS FORSELFUNLOADING CEMENTCARRIERSA COMPARISON H W CARLSEN UNLOADING SYSTEMS FOR SELFUNLOADING CEMENT CARRIERSA COMPARISON In principle there are five different types of selfunloader systems marketed by H WCarlsen today, even if you now and then can see combinations of these basic types aswell as modified versions of the same supplied with additional equipment to meetmarket requirements:1) The Carlsen DR Pump SystemOur most wellknown and the basic system for selfunloading cement carriers isthe Carlsen DR (Double Reloader) Pump System. This system is not particularlynew. The principle remains the same as when originally introduced around 40years ago, only that basically all components and the control system have beensubstantially upgraded and more and more refined over the years in order to gethigher unloading
rate and less maintenance without investing more money.With this system the cement is sucked from the holds into one of two “reloader tanks” by means of vacuum pumps and during the next cycle the cement is blown ashore to the silos by means of compressors.This pump system is combined with a unique fluidization system in the holds of the ships, which by today typically has been copied by most of our competitors as well, as it without any doubt is the most cost effective way to fluidize the cement, while it at the same time saves weight.The characteristic thing for the Carlsen type of hold fluidization system is thatthe fabric is laid out directly on the inclined tanktop and fixed to the same byflatbars and bolts along the sides only instead of adding ordinary heavy boxtype open top airslide conveyors, side by side, on top of the inclined bottom.From the low points in the holds the cement is sucked to the reloader tanks.By means of automatic valves the two reloader tanks are filled and emptied, oneafter the other, making the flow of cement to the silos in principle continuous,even if of batch type. The reloader tanks as well as the machines can be installed either on deck(preferred for conversions as it both saves volume in the holds and is easy toinstall) or between bulkheads below deck (preferred for newbuildings as the lostvolume can be compensated by making the ship somewhat longer and becausethe deck then becomes clean without any machinery room, hatch covers etcwhich in total means a lower cost and less ship maintenance).The pneumatic Carlsen Pump System can naturally also be completed in variousways to make it possible to unload the ship mechanically/by gravity over theship´s side. Several such ships with combined mechanical/pneumatic unloadingsystems of Carlsen design (as well as with combined mechanical/pneumaticloading systems) are in operation all over the world.2) The Carlsen Screw Conveyor SystemIn this type of selfunloading systems we instead of sucking the cement from thelow points in the holds use vertical screw conveyors to bring the cement upabove deck level. These are then in principle replacing the suction pipes of theDR pump system and standing centric in the holds.To be able to make maintenance to the screw conveyors these, however, haveto be installed inside vertical ducts (service shells) of approx 2 by 2 mtr goingfrom tanktop level to deck level, while the suction pipes in a DR system just gothrough the holds, as they are, as pipelines naturally do not need anymaintenance or service.Once on deck each vertical screw conveyor drops its cement into longitudinalscrew conveyors or airslides going along the whole ship for collection of thiscement.In the centre of the ship the cement finally normally is transferred from thislongitudinal screw conveyor or airslide system into a discharge screw conveyor installed on an outloading boom for gravity loading of the cement over theship´s side onto f.e. a belt conveyor on shore or directly into a bulktruck.Alternatively if pneumatic unloading is required, a blow tank system is added inthe centre of the ship, either on deck or between bulkheads below deck, intowhich the cement is fed by the above screw conveyor system.Screw conveyor dimensions as well as additional blow tanks and compressor sizes for the same are designed to match ship size and unloading capacityrequirements mechanically and/or pneumatically. 3) The Fuller Kinyon Pump SystemThe oldest cement pump system on the market is the Fuller Kinyon PumpSystem.This system originally was marketed by our sister company Fuller in theUSA and is in principle the same system as nowadays offered by ClaudiusPeters and IBAU.This type of system is a pure pneumatic selfunloader system, where one as stduses airslide channels of box type for installation on top of the sloping tanktopsin the holds, for feeding of the cement directly to their respective cementpumps.As there is no special cement pick up system from the holds, when using thiskind of pump, normally several pumps have to be spread out at tanktop levelalong the centre line of the ship for direct feeding from the airslides in theholds. Consequently also a big longitudinal triangular-shaped service tunnelhas to be arranged along the centre line throughout the whole ship for accommodating these pumps as well as the compressed air pipes, thefluidization blower pipes and cement transportation pipes. The compressorsrequired for the pumps and the blowers for fluidization can be installed midshipin a deck house alternatively between bulkheads at tanktop level.For high capacity unloading these systems require several parallel pipelines tothe silos and also several blowers for fluidization, as all pick-up points have tobe fluidized simultaneously. High pressure compressors can not be used either as this kind of pump can not handle high pressure.Due to the requirements of the big heavy and costly service tunnel as well asthe
use of std box type airslides in the holds and consequent loss of carryingcapacity of the ship, this type of system is in principle never used for conversions.On top of that, this type of system requires more energy than other systems onthe market for unloading pneumatically.For newbuildings the situation is different, as then it is possible to incorporatethe steel structure when calculating the overall strength of the ship. Also thelost cargo volume then can be compensated by giving the ship some extravolume.Although very energy consuming the reliability of this kind of system is veryhigh. It is a very simple straight forward system easy to understand andoperate, why it still is preferred by some shipowners.
4) The Carlsen CSP SystemNaturally H W Carlsen has a pneumatic system of “suction-only” type as well. Thisis called the CSP (Continuous Suction Pump) System. Here the cement is suckedfrom the fluidized holds into a special filter vessel (the CSP-tank), from where thecement is discharged mechanically via a special screw conveyor at its bottominstead of pneumatically as in case of the DRPump System described before. Thissystems is useful, when there is no requirement to pump the cement onwards tosilos but all cement is unloaded by gravity directly on the quay f.e. into trucks or onto a belt conveyor.The CSP-System has been on the market for over 20 years now and is used inmany installations all over the worlds.For independent shipowners on today´s market a DR-System with some additionalequipment for mechanical discharge, however, must be recommended before a“suction only” system like the CSP for maximum flexibility and general availability.5) The Carlsen 3-tank System The idea with this system is that instead of having ordinary DR-tanks, where eachtank has its own filter, a separate suction tank with the filter inside will be installedon top of two or more standard blow tanks in the central unloading machineryroom onboard the ship.This way the suction from the holds can continue all the time at full capacity, whilethe blow tanks are filled and emptied independently underneath.Simultaneously the overall efficiency of the system will be even higher than for anordinary DR-Pump System with an even lower power consumption/ton cementunloaded.As this 3-tank system requires more height than the DR-System, it is specificallyrecommended for big selfunloaders with high unloading rate requirements andwhere the tank system can be installed below deck in f.e. a service pump room inthe centre of the ship.Several systems like this are already in operation in shorebased shipunloadingterminals with excellent results and we have one system under delivery for a 15.000dwt selfunloader at present as well.
Unloading System Comparison In order to break down the system evaluation into an easily understandablecomparison I have concentrated the comparison to selfunloaders with pneumaticunloading capabilities, as this is the general market trend and what customers requirenowadays irrespective of ship sizes.Just to be able to discharge mechanically over the ship´s side is normally not enoughon today´s market, where most shore terminals just have some silos with packingequipment at some distance from the port and one or two pipelines between the quayand silo roof.This gives a very simple terminal operation with no transportation system to maintainand worry about, so it is very easy to understand, why it is preferred by many terminaloperators/owners.So, even if a typical mechanical unloading system is selected by the shipowner, it hasto be combined/completed by a pneumatic pump system for blowing the cement to thesilos.As the CSP-System is a suction-only system without pneumatic pumping capability,this system consequently has been left out in this evaluation. So, has the 3-tanksystem as this, as a system, is very similar to the DR-tank system but better in allways, when it comes to both performance and maintenance, only restricted by itssomewhat bigger height. Consequently it is enough to compare the ordinary DR-PumpSystem with the other systems and then all what the DR-Pump System is better at, the3-tank system is even better at.So, in principle I will compare three out of above five basic unloading system types.Furthermore I have restricted the comparisons to newbuildings, as the differences areminor between newbuildings and conversions for both the DR-Pump System and thecombined screw conveyor/blow tank system, while the original Fuller Kinyon
PumpSystem can in principle anyway not be considered, when it comes to conversions asmentioned before.In order to make the comparison generally valid, it has been split up onto threedifferent ship sizes (5.000 dwt, 10.000 dwt, 20.000 dwt) covering the most relevant shipsizes used as selfunloading cement carriers.Furthermore the nominal unloading rate for all installations for comparison has beenset to 500 t/h over 100 m total pumping distance including 50 m vertical lift at the silo.For longer distances all systems in principle require the same amount of additionalcompressor capacity, so what is relevant at 100 m is relevant also over longer distances. System Comparison for Pneumatic Cement UnloadingStd formulas used for power consumption calculations;Vertical Screw Conveyors: 0,015 x L x t/hHorizontal Screw Conveyors: 0,007 x L x t/hPneumatic Transportation over 100 mtr: 1 kWh/tonA) 5.000 dwt NewbuildingsList of major equipments required:1) The Combined Screw Conveyor & Blow Tank System:4 pcs 10 mtr long, 22 kW 125 t/h vertical screw conveyors in the holds,2 pcs 25 mtr long, 37 kW 250 t/h horizontal screw conveyors on deck,1 set double Blow Tank System with feeding hopper on top plus1 pc 650 kW, 150 m3/min, 3,5 bar compressor for blowing the cement to the silos,4 pcs 75 kW blowers for fluidization of the holds,2 pcs 11 kW deckfilters,1 pc 7,5 kW high pressure compressor for filter cleaning and valve manoeuvring,fluidization matting, butterfly valves, pinch valves, flow gates, control panel etc.Total Power Installed: 1140 kWAverage Power Consumption: 825 kW or 1,7 kWh/ton cementbased on 500 t/h unloading rate in one 100 mtr long 14 inch pipeline to the silosDrawback:Due to high equipment cost and high energy consumption as std both holds haveto be unloaded in parallel to save on screw diameters, installed power andinvestment cost. This way f.e. only one cement quality can be unloaded at full rate.If instead full capacity is required from one hold at the time, the vertical screwconveyors become 45 kW each and the horizontal ones 75 kW each. On the other hand only two 75 kW blowers now are required for fluidization. Therefore in thiscase the total power installed becomes 1.160 kW, while the average power consumption becomes 760 kW or 1,5 kW/ton.So this way the power consumption becomes lower, while the investment andinstalled power, however, become higher. 2) The Fuller Kinyon Pump System:4 pcs 90 kW cement pumps plus4 pcs 160 kW, 43 m3/min, 3 bar compressors for blowing the cement to the silos,4 pcs 75 kW blowers for fluidization of the holds,2 pcs 11 kW deckfilters,1 pc 7,5 kW high pressure compressor for filter cleaning and valve manouvring,fluidization channels for the holds, butterfly valves, pinch valves, flow gates,control panel etc.Total Power Installed: 1.325 kWAverage Power Consumption: 1.020 kW or 2,0 kWh/ton cementbased on 4x125 t/h unloading rate in four parallel 100 mtr long 8 inch pipelines tothe silosDrawback:Besides the highest power consumption of the three systems the pumps have toblow in parallel all the way to the silos in four 8 inch pipelines instead of in onesingle 14 inch line in order to achieve the total average unloading rate required.The piping cost for this system therefore is more costly than that for the combinedscrew conveyor/blow tank system and Carlsen DR Pump System.If the ship carries two types of cement does, however, not matter in this case, asthe cement from the different holds anyway is pumped in different pipelines all theway to the silos as a std. 3) The Carlsen DR Pump System:1 pc 160 kW vacuum pump for sucking the cement from the holds,1 set DR-tanks,1 pc 650 kW, 150 m3/min, 3,5 bar compressor for blowing the cement to the silos,1 pc 90 kW blower for fluidization of the holds,2 pcs 11 kW deckfilters,1 pc 7,5 kW high pressure compressor for filter cleaning and valve manoeuvring,fluidization matting, butterfly valves, pinch valves, control panel etc.Total Power Installed: 930 kWAverage Power Consumption: 700 kW or 1,4 kWh/ton cementBenefits:Besides having the lowest power consumption of the three systems also as std fullunloading capacity can be achieved from one hold at the time and only one 14 inchpipeline is required to the silos. No mechanical handling of the cement also meanslowest possible wear and maintenance cost combined with highest possibleavailability.Drawbacks:NoneSummary:The Carlsen DR Pump System is superior in all respect, when it comes topneumatic unloading of 5.000 dwt ships.
B) 10.000 dwt NewbuildingsList of major equipments required:1) The Combined Screw Conveyor & Blow Tank System:4 pcs 11,5 mtr high, 30 kW 125 t/h vertical screw conveyors in the holds,2 pcs 30 mtr long, 45 kW 250 t/h horizontal screw conveyors on deck,1 set double Blow Tank System with feeding hopper on top plus1 pc 650 kW, 150 m3/min, 3,5 bar compressor for blowing the cement to the silos,4 pcs 75 kW blowers for fluidization of the holds,2 pcs 11 kW deckfilters,1 pc 7,5 kW high pressure compressor for filter cleaning and valve manoeuvring,fluidization matting, butterfly valves, pinch valves, flow gates, control panel etc.Total Power Installed: 1.190 kWAverage Power Consumption: 880 kW or 1,8 kWh/ton cementbased on 500 t/h unloading rate in one 100 mtr long 14 inch pipeline to the silosDrawback:Due to high equipment cost and high energy consumption as std both holds haveto be unloaded in parallel to save on screw diameters, installed power andinvestment cost. This way f.e. only one cement quality can be unloaded at full rate.If instead full capacity is required from one hold at the time, the vertical screwconveyors become 55 kW each and the horizontal ones 75 kW each. On the other hand only two 75 kW blowers now are required for fluidization. Therefore in thiscase the total power installed becomes 1.200 kW, while the average power consumption becomes 790 kW or 1,6 kW/ton.So this way the power consumption becomes lower, while the investment andinstalled power, however, become higher. 2) The Fuller Kinyon Pump System:4 pcs 90 kW cement pumps plus4 pcs 200 kW, 43 m3/min, 3 bar compressors for blowing the cement to the silos,4 pcs 75 kW blowers for fluidization of the holds,2 pcs 11 kW deckfilters,1 pc 7,5 kW high pressure compressor for filter cleaning and valve manouvring,fluidization channels for the holds, butterfly valves, pinch valves, flow gates,control panel etc.Total Power Installed: 1.490 kWAverage Power Consumption: 1.070 kW or 2,1 kWh/ton cementbased on 4x125 t/h unloading rate in four parallel 100 mtr long 8 inch pipelines tothe silos plus in average 15 mtr additional pumping distance onboardDrawback:Besides the highest power consumption of the three systems the pumps have toblow in parallel all the way to the silos in four 8 inch pipelines instead of in onesingle 14 inch line in order to achieve the total average unloading rate required.The piping cost for this system therefore is more costly than that for the combinedscrew conveyor/blow tank system and the Carlsen DR Pump System.If the ship carries two types of cement does not matter in this case, as the cementfrom the different holds anyway is pumped in different pipelines all the way to thesilos as a std.
