Author: Dr. Theo Notteboom

Dry bulk and liquid bulk terminals have a diversity of terminal designs and functions and a broad range of quay, yard and warehousing equipment.

1. Bulk Market Segments and Vessels

The term bulk refers to commodities that are transported in very large quantities. Three major components impact bulk markets:

• Supply characteristics. Resources carried by bulk are extracted according to geographic (minerals and fossil fuels) and climatic conditions (agricultural goods and wood products). Some, such as coal, iron ore, and petroleum, have a high concentration level, while others, such as agricultural goods, are collected over extensive areas. In all cases, bulk commodities require substantial storage capacity.
• Demand characteristics. Each bulk market has a demand-pull related to intermediary processing and manufacturing activities. The location of these facilities, usually adjacent to port sites, considers the demand for the resources over an extensive market and a material index (ratio of inputs over outputs). The demand for bulk commodities is usually managed by large commodity traders and brokers who can consolidate purchases and distribute large quantities.
• Potential for economies of scale. The economic rationale for using the largest ship size possible, considering the geographical distribution of supply and demand, is fundamental in the bulk market. This potential is limited by the characteristics of the waterways at the port of origin, in transit (e.g., Panama, Suez), and at the port of destination. The outcome is a wide range of bulk ship classes trying to reconcile supply, demand, and economies of scale.

There are three main bulk markets, each consisting of several sub-markets:

• Major dry bulk commodities include iron ore, coal, and grains. They are not homogeneous, as there are several grades of coal used for making steel (coking coal) and energy generation (steam coal). Each represents a different market, implying a segmentation of the bulk trades.
• Minor dry bulk commodities include cargoes such as fertilizers, bulky agricultural products, cement, sand, petroleum coke, and metal scrap. While major bulks are often loaded in large bulk carriers (such as Capesize and Panamax vessels), minor bulks are usually transported by sea in smaller and more versatile vessels such as handymax ships and coasters. The term minor bulk is derived from the potential economies of scale that can be realized due to market size and demand patterns that are more dispersed than for major bulk trades.
• Liquid bulk includes products in liquid and gaseous forms, such as crude oil, oil products, LNG, and LPG. These products are shipped by oil tankers, chemical tankers, parcel tankers, and gas carriers. The oil tanker fleet consists of various ship sizes and has been particularly prone to economies of scale considering the global demand for petroleum, one of the most extensively traded commodities. A common size is the Very Large Crude Carrier (VLCC) of around 200,000 dwt. LNG carriers can be grouped into different sizes depending on the trade route concerned and service a market that has seen rapid growth. Chemical and parcel tankers are designed to carry an assortment of liquids, such as chemicals, or different grades of a liquid, like petroleum, at one time. They usually have a capacity in the range of 25,000 to 80,000 dwt, although smaller units are used for coastal trade.

2. Dry Bulk Terminals

A. Major Dry Bulk Terminals

There is an important directionality to major bulk trade, implying that export bulk terminals (mainly for coal and iron ore) are designed rather differently from import bulk terminals:

• Export terminals. Combine stacker reclaimer systems and ship loaders to connect the yard to the bulk carriers. A good example of a major export terminal for dry bulk is Port Hedland in Australia, the world’s largest coal export port. Export terminals facilitate outgoing cargo flows and are strongly synchronized with the inland transport system (mostly rail-based) that connects the mining areas to the terminal. Export terminals try to limit stocks but sometimes must keep a large (unsold) stock to support commodity trade pricing. In most cases, export terminals handle a limited number of material types due to their location in relation to mining areas or due to their ownership, as many export terminals are owned by traders or mining companies. The location of many export terminals is a compromise between hinterland and maritime accessibility.
• Import terminals. Use unloaders equipped with large grabs to discharge the commodities. There are several types of quay cranes and grabs available. The choice of the crane type depends on the operational needs of the terminal operator in terms of ship sizes to be served and minimum cargo handling productivity in tons per hour. Conveyor systems transport the discharged commodities along the quay and onto the yard. As import terminals usually handle multiple types and grades of major bulks, stockpiles of bulk material are spread across the yard. The terminal surfaces of import terminals are quite large to avoid cross-contamination between stockpiles and comply with necessary certification requirements. Stacker reclaimers are used to transport the bulk products from the yard to the loading stations for seagoing vessels, inland barges, and railcars. A good example of a major import terminal for dry bulk is EMO in Rotterdam, one of the largest dry bulk terminals in Europe. Import terminals for handling major bulks rely heavily on rail and barge (where available) for hinterland transportation. They have to match services to both the waterside and the landside modalities. The most advanced bulk terminals are equipped with automated railcar loading/unloading systems. Terminal planning is quite challenging as vessels usually arrive in a stochastic manner (random along a probability distribution), and the consignee selects landside services and inland modalities.

Coal and iron ore terminals might offer additional services such as washing, screening to separate the bulk material into different grades, blending silos, and compacting to prevent spontaneous combustion. Terminals limit environmental effects by investing in technology to save energy and reduce noise and dust emissions.

Dust control is a key concern at dry bulk terminals. Whenever a transfer of coal or iron ore occurs, there is a potential to break the lumps, resulting in dust, which can be spread by crosswinds. Once the coal or iron ore is stockpiled, dust can still be a problem. Even if it arrives wet, wind across the stockpile can evaporate the moisture, and dust will be lifted. Any vehicles driving over crushed lumps will also raise dust. Several measures are taken to reduce dust emissions, such as:

• Dust covers on grabs and conveyors.
• Fogging systems that release small droplets of water into the air, forcing dust to precipitate.
• Sprinkler systems spray water on stockpiles to keep them damped down. This includes an adapted drainage system and on occasion a water recycling station.
• Optimized stockpile design, such as avoiding edges that can dry quicker than a rounded surface.
• Add a protective layer over the stockpile, such as a skin formed by a water additive.
• In the case of loading operations in the vessel holds, loading chutes with heavy-duty dust skirts can be used in order to prevent dust cloud formation arising from the product falling onto the peak of the product pile in the hold.

The capacity of a dry bulk terminal to transload coal or iron ore is determined by many factors, such as the quay length, the yard dimensions, the quay and yard equipment, the stockpile patterns and heights, the storage time distribution of the bulk material, the number of types and/or grades handled, the terminal operating hours (waterside and landside), the arrival patterns, types and sizes of ships and land transport modes. The use of an existing terminal can be further optimized by improving berthing/unberthing procedures, optimizing vessel traffic rules, synchronizing vessel and landside operations, reducing downtime (caused by hatch changes, shift changes, or breakdowns), and installing provisions that allow all-weather operations. In some cases, dry bulk is not handled at terminals, but using offshore handling facilities.

Grain terminals are designed to handle and store wheat, soy, and other grains and oilseeds. Their core purpose is to act as major collection and distribution points, but also as storage facilities to deal with the seasonality of grain production, compared with a much more stable demand. There are many models of both discontinuous systems (such as those using grabs) and continuous ship unloaders (CSU), including pneumatic chains, screws, or twin-belt machines. Grain elevators stockpile or store grains using bucket elevators or pneumatic conveyors that scoop up grain from a lower level and deposit it in a silo or other storage facility. Large grain terminals can have dozens of large silos located next to each other. Many grain terminals offer additional services, such as cargo sieving in order to calibrate the grain, and fumigation. Many factors influence the performance of unloading systems, such as ship type and size, type of product, the number of product impurities, product density, adverse weather conditions, and downtime.

B. Minor Dry Bulk Terminals

Just like for major bulks, minor bulks are placed or poured into cargo holds. The terminal superstructure includes:

• Cranes and conveyors. Portal quay cranes, jib cranes, mobile cranes, floating cranes, and loader/unloader systems are deployed to load and discharge minor bulks, combined with conveyor and elevator systems where required. The cranes are equipped with specialized grabs, mostly of the clamshell type. The grabs can be operated by ropes (single-rope, two-rope, or four-rope clamshell buckets), electro-hydraulically or by diesel hydraulically.
• Yard and warehouse vehicles. The cargo handling operations are supported by different types of yard and warehouse vehicles such as bobcats, tractors, trailers, forklifts, and front-end loading shovels (fitted with a pusher).
• Other equipment at the yard and the covered storage facilities can include weighbridges, hoppers (where the product is loaded into trailers or trucks), blending silos, and bagging plant facilities.
• Minor bulk storage facilities can be in the open air or covered in warehouses and are typically sectioned off into separate bays to enable various products or grades to be stored.

Minor bulk terminals face a wide range of possible operational risks, such as cross-contamination of cargo types, water ingress, and fire/ignition/explosion hazards. Handling bulk ships can be rather dangerous, with specific rules and regulations related to cargo movement and immersion.

3. Liquid Bulk Terminals

Due to the nature of the commodities they handle liquid bulk terminals are radically different from dry bulk terminals since they are equipped to handle cargoes in liquid and gaseous forms, such as crude oil, oil products, LNG, and LPG.

The loading and unloading of tankers needs special equipment such as loading hoses or loading arms. These loading arms include safety accessories and are often geared with remotely operated quick couplers. Loading arms consist of a piping assembly with moveable pipes. The flexibility is achieved by swiveling joints. Because of the high weight of the steel piping, the moveable pipes are counterweight-balanced. The loading arms can have one or two liquid lines and, if needed, can be equipped with a vapor line. The loading arms can be installed on jetties or regular quay walls. Due to these characteristics, liquid bulk terminals tend to use jetties as berth areas since limited activity outside pumping occurs on the dock.

The yard of a liquid bulk terminal usually contains a mix of tank storage facilities and other technical installations, such as pump stations. Many liquid bulk terminals are directly connected by pipeline to chemical or petrochemical production sites. The storage tanks rely on two storage methods:

• Fixed roof tanks. They tend to be used for unrefined petroleum products (crude oil) and may require a heating system to keep the product viscous and easier to pump.
• Floating roof tanks. The tank roof floats over the stored product and varies according to the quantity. They are used for more volatile products, such as gasoline.

The capture and recovery of hydrocarbon vapor or volatile organic compounds (VOC) to reduce emissions is vital in modern oil and gas terminal handling and storage. The requirements for the vapor recovery systems depend on the type of product handled and stored. Vapor from the cargo tanks passes through a vapor head to a recovery unit. Sulfur components in the vapor are removed before entering the vapor recovery system.

Related Topics

• Chapter 3.1 Terminals and Terminal Operators
• Chapter 3.2 Terminal Concessions and Land Leases
• Chapter 3.7 Dock Labor
• Chapter 3.8 Terminal Automation
• Chapter 8.1 Cruise Ports
• Chapter 8.2 Break-Bulk

References

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• Further references to be added