Modular construction hasn't gained the role it deserves for pilot plants. Our experience at ExxonMobil Research and Engineering shows that building pilot plants in one central facility whenever possible for shipment and installation around the world makes a lot of sense.
The approach is based on building units in sections that readily can be transported by road, rail or sea depending on the final destination. Road transportation is most common and also most restrictive. Larger modules are possible but become significantly more costly and impose more limitations on routes available. Standard road-transportable sizes are more than adequate for most pilot plants and even small-scale demonstration units. You simply design the modules to be smaller or to come apart for shipment.
Modular construction isn't a new idea; the petrochemical industry has used it for decades. However, it's often just considered for avoiding onsite construction in inhospitable or inaccessible locations like the North Sea or in areas with inadequate infrastructure. In these cases, it may be the only practical option. However, the approach offers many benefits for projects that don't suffer from these obvious handicaps.
Modular construction allows most pilot plants to be fabricated in a controlled environment, typically a shop specializing in modular or pilot-plant and laboratory unit construction. Shop construction always is more efficient than field construction because it can eliminate or at least minimize many inefficiencies and variables affecting productivity.
The work area usually is enclosed and protected from the weather. The room around the construction area generally is more open for access from all sides and is organized for greater efficiency. Section fabrication, layout and assembly often can take place on large worktables. Scaffolding or rolling platforms can surround larger components to reduce inefficient ladder use. Cranes and hoists -- permanent or temporary -- may be on hand to move and place larger equipment. Welding equipment or outlets are readily available.
Temporary construction power is easier to provide and usually already conveniently distributed around the work area. Specialty tools can be justified due to repeated use and result in significant cost savings. Stock rooms, equipment bins and similar materials storage can be set up nearby in a convenient location.
Operating restrictions such as permits, black-out times and access limitations are eliminated -- and with them, the time spent obtaining permits and clearances, accommodating operational needs, keeping traffic corridors open, relocating tools or equipment as operations require and a host of similar issues.
Shop construction also promotes a steady crew size. Field construction often involves obtaining new craft workers, training them in procedures and practices, and then releasing them at project end, losing all accrued orientation and experience. Shop construction frequently can be scheduled to keep the crews for longer periods -- thereby eliminating repeated training and learning curves.
The approach also increases quality because the shop conditions promote better work. Climate control ensures components aren't assembled in high humidity or bad weather that may result in internal corrosion, water or dirt damage. The proximity of specialty equipment allows better quality construction. Inspections usually are easier and more routine.