LNG Heat Exchanger Assembly System

Manufacturer for LNG heat exchangers uses Wheelift® transporters within their existing facilities for core insertion, sub-assembly buildup, and final assembly

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CHALLENGE: Transfer and position loads up to 15' diameter x 70' long and weighing 220 tons throughout manufacturing and assembly within existing facilities that are compromised by uneven surfaces, low ceilings, obsolete rail tracks, outside ramps, and fixed machinery locations.

SOLUTION: Provide two self loading 110-ton capacity Wheelift® transporters, each capable of operating independently or jointly (tandem) as a single 220-ton capacity Transporter.

BENEFITS:

• Increased plant utilization eliminating the need for a previously planned expansion.
• Increased productivity by shortening all move times with manpower reductions.
• Provided greatly improved process flexibility through eliminating use of inflexible rail carts and overhead cranes
  

Heavy transportation and manufacturing system

This first-of-its-kind heavy transportation and manufacturing system is at  Air Products and Chemical's (APC), Heat Exchanger manufacturing plant in Pennsylvania where they build massive heat exchangers that will liquefy natural gas for ocean going LNG tanker shipments. Manufacturers like APC and Linde Engineering out of Germany now have the capability of building larger heat exchanger components than previously possible due to the space limitations in plants that could not handle larger size loads needed to meet market demands.

These 110-ton capacity heat exchanger transporters are designed for use throughout the entire manufacturing, sub-assembly and final assembly operations. With their low mounted LPG engines and low profile axles, they have deck heights of only 24" and have the capability to lift and lower eight inches for self-loading and surface compliance. Each of the two transporters has nine on-center rotation axle assemblies. With their computerized fluid equalizing suspension, lateral tilting axles and interconnecting fluid lines, their computer controlled lift zones assure that every wheel carries only its specific share of the load, regardless of variations and irregularities in the floor surfaces. Floor loading is dispersed with ground pressure loads spread over a wide footprint.

To reach the next heat exchanger assembly location, the Wheelift Transporters are individually driven and positioned under a core assembly that is to be removed from one of their many tube winding stations. Each core consists of literally hundreds of miles of small diameter aluminum tubing wrapped around a large diameter pipe core. These large diameter pipe foundations are often up to 40 feet in length. The strands of tubing are wound onto the core pipe beginning at one end and terminating at the other over a period of several months. The tube wrapping process results in a finished heat exchanger core that is 15 feet in diameter and weighs nearly 220 tons.

Wheelift Transporters

To remove the finished heat exchanger core from the winding machine, the Wheelift® transporters are positioned near the winding machine's chucks at each end of the completed heat exchanger core. Large-radius chocks are placed on the transporters' low decks. The low deck heights are critical to allow the transporters to get under the finished cores to remove them from the winding machines.

With the chocks in place, the transporters raise and relieve the weight from the winding machines chucks. The chucks are released and withdrawn enough to allow the core center pipes clearance for removal. With the finished cores fully supported by the two transporters, the transporters back out to clear the winding machine. The two transporters are now operating in "tandem", that is to say, the two transporters now function as one. The SynchroSteer® computer on one transporter becomes the "master" and the other the "slave", allowing the two transporters to function as a single 18-axle, 36-wheel transporter with fully synchronous omni-directional steering. Movement and positioning of the tandem operating transporters is controlled from a single hand held controller.

With fully equalizing suspension, the transporters are driven through highly congested portions of the plant, encountering low ceilings and many fixed location machines. They cross numerous unused in-floor rails as they travel over the typical deteriorated floors of the old plant they are operating in. The finished heat exchanger cores travel a winding route through the old plant to a new expanded assembly area where the cores are to be inserted into the heat exchanger's outer shells.

The outer heat exchanger shells are held on raised cribbing to hold them at the right height for core insertion. The outer heat exchanger shells have a close tolerance inside diameter. The transporters nimbly align the two components and then insert the leading end of the core into the outer shell. The bottom surface of the outer shell has two strips of high density material that act as sliding surfaces. With the end of the core sufficiently inserted into the outer shell, the lead Wheelift transporter lowers to transfer the forward edge of the core onto the sliding surface. With the chocks removed, the lead transporter exits from under the heat exchanger core, while the trailing transporter travels independently to support and assist with powering the travel of the heat exchanger core as it slides fully into the outer shell.

The transporters play a MAJOR role in how this plant is now able to operate. The company has been able to almost TRIPLE their production and reduce the prior typical 11-month build schedule to less than 9 months. The ability to handle these massive and otherwise extremely difficult packages effortlessly through twisting travel paths has provided this plant with versatility that cannot be imagined by any other means.

At the marry-up station, the transporters orient the loads to precise locations for mating multiple heat exchanger components. When fully assembled the heat exchangers are shipped via dedicated special trains that transport the completed heat exchangers to US seaports.

The Modular Wheelift Chassis provides a degree of flexibility not obtainable through other technologies. Wheelift Transporters and AGVs enable manufacturing flexibility with configurable work processes, facilitating new design freedoms benefiting worldwide niche markets.

Wheelift® Transporters and AGVs are manufactured in Iowa and are custom engineered to application specific requirements. Chassis and fixtures are available with load capacities to 500+ tons and deck heights as low as 18.5". Power options include diesel, LP gas, battery, and/or umbilical cord. Computerized all electric omni-directional drives are standard with individual axle ratings of 15, 20, or 30-ton.

Wheelift® is a Doerfer Companies technology. Doerfer engineers and builds application specific manufacturing machinery and systems. Operating from four North American locations with over 700,000 sq. ft. and 500+ employees, Doerfer offers an array of engineering and manufacturing resources and is NQA-1 certified.

SUMMATION: For products the size of LNG heat exchangers, Wheelift transporters provide major improvements and flexibility in the assembly processes usage of existing spaces — making it possible to increase production without major changes to the plant.

TRADEMARKS

The following terms that are used through this website: Wheelift^®, Uniload^®, SynchroSteer^®, StackAxle^®, TrackAxle™ and OmniAxle^™ are all trademarks that are exclusively licensed to Doerfer Companies.