Environmental pressures and changing commodity trades mean covered storage options are worth another look.
The market for covered storage continues to edge up as dry bulk terminals look to diversify the range of materials they handle.
Biomass is certainly one growth area, but housing stockpiles under a roof is also driven by speciality minerals and agricultural produce, which risk degradation if left outside. In many cases, a forecast decline in demand for legacy minerals, like coal, is freeing up land in densely packed terminals.
This was the case at European Bulk Services (EBS), which announced earlier this year an expansion of its covered storage facilities in the Port of Rotterdam. At its Laurenshaven terminal, EBS will construct 126,000m3 of storage sheds. In addition, EBS plans to put up a 40,000 m3 storage shed at its Europoort terminal.
These new multipurpose warehouses are in addition to the existing 525,000 m3 covered storage, bringing the total capacity to 691,000 m3 . At the end of May, EBS took a 60,000 m3 storage shed into operation the commissioning of which was announced in June 2016. This shed, supported by a long term contract, is suitable for various dry bulk products.
Engineering and construction companies Cordeel, Tosec and TES constructed the multipurpose storage shed for EBS in nine months, within the agreed deadline and timeline.
The concrete shed on the quay is made up of six compartments, each of 10,000 m3 . The hatches are mobile, and are operated remotely by the crane drivers. An advanced security system prevents the grab of the crane damaging the walls of the shed, while the roof is fully insulated and prevents condensation from forming.
Managing director Jan de Wit said the new capacity will allow the terminal operator to better serve the demand for storage in Rotterdam. “By investing in state-of-the-art land-based facilities, we can reduce the cost for floating storage in barges, while improving the quality and safety of operations. The design will be carried out with a strong focus on flexibility for our customers, and our safety and environmental standards,” he commented.
The move followed the announcement by EBS parent company HES International to grow its bulk liquid storage business. HES CEO Jan Vogel said the group’s strategy is to become a European market leader in the handling of bulk products that require covered storage, such as agricultural products, biomass and speciality minerals. The expansion of warehouse facilities will also be pursued in other European ports.
The new shed at the Laurenshaven will be equipped with a new crane, and will also be suitable for minerals, biomass and agricultural products. Construction will occur on land previously used for coal storage, and is expected to start immediately after receipt of the building permit.
Dome manufacturer Geometrica has raised the question of whether open bulk storage yards are a thing of the past. That might be considered as unrealistic, but an increasing need for environmental compliance is, in some cases, driving uncovered stockpiles under cover at mines, ports, power stations and cement plants.
Based in Cypress, Texas, US, the company argues that it takes more than conventional building construction techniques to overcome the obstacles frequently confronted on some storage sites. These include remote locations, often with a rugged, sloping terrain. The climate can be adverse, and the stockpile to be housed can be an irregular shape, and limited to a confined area.
Traditional building solutions with joists, for example, are limited to planar trusses in an array, and work in only one direction on level ground. Solutions with machined joints, such as ball-joint systems, are expensive and must minimise the number of nodes.
Geometrica claims that its freestyle, geodesic domes – marketed as Freedome – can enclose irregularly shaped stockpiles on any terrain. The superstructure can span 300m without any interior columns.
The technology evolved from gridshell innovations originally developed in the 1960s. Today, domes can be designed with a non-circular plan in varying curvatures, for greater design freedom. Freedomes may have lamella, kiewitt or combination patterns, with a single or double structural layer. Once the geometry and support requirements are defined, Geometrica’s engineers can propose the most efficient patterns and layer options for an enclosure.
Clearances needed for vehicles and equipment, personnel access, and maintenance are accommodated during the design work, and, crucially, the company understands that many stockpiles must remain in operation while being covered.
Geometrica offers three different assembly methods – lift-in-place, perimeter self-supporting, and centreout. The option chosen is determined by the specific site requirements, operational requirements, as well as the structure’s design.
Stockpiles can remain in operation while being covered, and it can be accomplished without heavy machinery, scaffolding or welding.
One of the company’s most recent projects is in the Philippines. A coal stockpile located near the city of Toledo, in Cebu province, needed to be put under cover to house 180,000t of coal for a Therma Visayas 340 MW power plant.
The circular dome spans 125m in diameter, with a height of 40m. An area of approximately 11,500 m2 is enclosed with double-layer geometry. The cladding phase for the dome was completed in seven weeks. Corrosion resistant aluminium was used due to the site’s proximity to the coast. Designed with a wind tunnel test at BMT Fluid Mechanics, UK, the dome can withstand wind speeds of up to 66 m/s (147.6 mph).
Whether stockpiles are left open or not, there is concern in many quarters about the storage of commodities such as fertiliser.
Following the deadly blast in 2013 at the West Fertilizer Company plant in Texas, efforts by the Texas State Legislature to beef up oversight of hazardous materials storage have been “not entirely adequate,” the Chemical Safety Board (CSB), a federal agency, said in its final report on the disaster.
The West disaster, which killed 15 people, mostly first responders, was “one of the most destructive explosions ever investigated by the CSB,” said CSB chair Vanessa Allen Sutherland. The safety board “found that limited regulatory oversight, poor hazard awareness, inadequate emergency planning, and the proximity of the facility to nearby homes and other buildings all led to the incident’s severity.”
Another American manufacturer Monolithic Dome, based in Italy, Texas, argues that its smaller-scale domes make an effective storage structure for fertiliser because they are insulated. The effect is to retain the condition of the fertiliser for an extended time, because, as temperature changes, fertiliser also changes its properties. For example, it can harden and require more time to break up. There is also potential for the material to liquefy, which can eat into concrete. By keeping fertiliser in an insulated dome, the product stays in a pure state, the firm argues.
Each Monolithic Dome starts as a concrete ring foundation, reinforced with steel rebar. Vertical steel bars embedded in the ring are later attached to the steel reinforcing of the dome itself. Small domes may use an integrated floor/ring foundation. Otherwise, the floor is poured after completion of the dome.
An ‘airform’ – fabricated to the proper shape and size – is placed on the ring base. Using blower fans, it is inflated, and the airform creates the shape of the structure to be completed.
Polyurethane foam is then applied to the interior surface of the airform. Entrance into the airstructure is made through a double door airlock that keeps the air pressure inside at a constant level. Approximately three inches of foam is applied, and this foam is also the base for attaching the steel reinforcing rebar.
Then steel reinforcing rebar is attached to the foam using a specially engineered layout of hoop (horizontal) and vertical steel rebar. Small domes need small diameter bars with wide spacing. Large domes require larger bars with closer spacing.
The final step is shotcrete – a special spray mix of concrete – which is applied to the interior surface of the dome. The steel rebar is embedded in the concrete, and, once about 3 inches of shotcrete is applied, the Monolithic Dome is finished. Blower fans are shut off after the concrete has set.
In complying with the push to greater safety at fertiliser sites, Monolithic Dome erected a 29ft tall, 58ft diameter dome in Whitewright, Texas, to provide storage for ammonium nitrate. The dome is located at the EDC Ag Products Company facility, and will provide storage for 1,000t of the chemicals.
Although ammonium nitrate is a source of nitrogen fertiliser, by itself it is not explosive. However, it is an oxidant, and, when it comes in contact with a burning substance, it can add fuel to a fire. Storing products such as ammonium nitrate in domes offers a greater measure of safety from fire and possible explosion, the company claims.
It argues that domes help neutralise blasts created from inside, and block fires from the outside. There are approximately 1,300 facilities across the USA that store ammonium nitrate.
One of the world’s biggest manufacturers of storage silos and domes has been saved from bankruptcy.
CST Industries, which also builds bulk liquid storage tanks for oil terminals, reached agreement in November on the firm’s sale to asset management group Solace Capital.
CST filed for Chapter 11 bankruptcy protection in June this year citing a lack of liquidity caused by “a chain of events put into motion by one of CST’s large unsecured creditors, who rejected several attractive, formal letters of intent from third parties”, according to CEO Tim Carpenter.
The company’s problems stemmed from a downturn in oil and gas markets and in the Middle East water tank market, rather than in the dry bulk market. CST was forced to default on US$57.5M in senior secured debt, as well as US$114M in unsecured obligations.
In September, Solace offered US$93M for substantially all the assets of CST. Now the company will be rolled into a new entity, Solace CST LLC.