Products

1. The Trans Ocean Gas (TOG Inc) Solution

The TOG Inc solution to transporting CNG (and other gases) consists of installing large-diameter type-4 composite pressure vessels inside of standard ISO shipping containers. Under UN regulations, such a mobile gas storage system is defined as a multi-element gas container or MEGC. Using 8 (3000 liter) type-4 pressure vessels secured inside of an insulated 40-foot ISO container, the TOG Inc MEGC / mobile gas container will carry about 315,000 scf of CNG (at a temperature of minus 40 degrees Celsius). At this temperature and a maximum pressure of 240 Bar, the natural gas will exist primarily as a liquid called PLNG. In addition to being able to transport CNG and PLNG, the TOG Inc MEGC will also be practical for transporting hydrogen, liquid carbon dioxide, propane, nitrogen among many other gases. Figure 1 (shown below) is a drawing of the TOG Inc MEGC using 8 of its large diameter type-4 pressure vessels.

Figure 1: The TOG Inc Multi-Element Gas Container (MEGC)

2. The Trans Ocean Gas Type-4 Pressure Vessel

The TOG Inc pressure vessel uses a 1-meter diameter plastic liner made from an industry proven HDPE. The liner is made in two equally moulded parts. To wind carbon or fiberglass filament fibers around the liner, a computer numerically controlled (CNC) winding machine is required. Where the liner doubles as a mandrel during the winding process, stability and strength are critically important.

Integrated into the polar ends of the liner are stainless steel port end bosses. These are the portals which allow natural gas to enter and exit the pressure vessel. The polar port bosses are fabricated and assembled onto the end domes of the liner using proprietary hydraulic technology. hydraulic is used extensively in the aerospace and national defense industries. Notably, the connection requires no welding or threading. The half-liner assemblies are then butt-fusion welded together in the middle.
Once the liner is complete, it is placed onto a filament winding machine to become a mandrel. The winding machine rotates the mandrel to apply a ribbon of continuous filament fibers in precise helical and circumferential patterns. Just before being wound onto the mandrel, the fibers are impregnated with wet epoxy resin.
Once the winding of the filament fibers onto the liner is complete, the tacky/ wet pressure vessels are then placed in a curing oven until the epoxy resin has cured. Once cured, each pressure vessel is then hydraulically proof tested to 1.5 times operating pressure. On the success of proof testing, the pressure vessels are then ready and safe to use.

3. Trans Ocean Gas Pressure Vessel Characteristics

The TOG Inc pressure vessel is designed to withstand 750 Bar pressure. Using a factor of safety of 3.0, the allowable operating pressure will be 250 Bar. The operating temperature will range from -40 to +40 degrees Celsius. Once commercialized, lower temperature testing will be performed to prove integrity at even lower temperatures.

The regulatory life span of the TOG Inc pressure vessels is 15 years. However, by that time, it is expected that an additional 10 to 20 years will be allowed (with additional testing). Using carbon fiber to fabricate the pressure vessels, fatigue is not a concern.

4. Applications

The TOG Inc system using its proprietary type-4 pressure vessels have the following applications:

(a)Road and Rail Application (Carbon Fibre Pressure Vessels)

The TOG Inc mobile gas containers are very light-weight and very safe. They are also produced at the lowest cost per volume storage of any other mobile gas transportation system in the world.

Most recently, CSA Standards have been issued that adopt the principles of the UN regulations for MEGCs. On October 28, 2009, Transport Canada publicly issued a statement that it would approve MEGCs that conform to the recently issued CSA Standards B341 and B342. This is most fortunate timing for TOG Inc as it holds the patent rights for using FRP pressure vessels to transport CNG and PLNG in mobile containers.

By using high-strength carbon fiber the 40-foot MEGC will weigh about 16 tons empty. The weight allocation for a 40-foot shipping container is 30.48 tons for lifting or 34 tons on a trailer. The TOG Inc carbon fiber solution is therefore the most practical and feasible way to transport CNG by road or by rail.

(b)Marine Ship Application (Fiberglass Pressure Vessels)

For the marine transport of large volumes of natural gas by ship, a slightly different solution is proposed. Instead of using carbon fiber to make the laminate shell of the pressure vessels, the same high-density polyethylene (HDPE) liners with hydraulic polar port bosses are wrapped with continuous lengths of high-strength fiberglass. The pressure vessels will weigh significantly more, but the cost to produce will drop by approximately fifty percent. Notably, the strength of fiberglass increases with colder temperatures. Thus, additional benefit is gained through the use of fiberglass when refrigeration is used. Should the storage temperature be maintained below minus 40 degrees Celsius, the natural gas will liquefy at a significantly lower pressure. In turn, this will allow for a lower production cost, increasing potential project feasibility. For a ship-based application, the supporting structure is similar, but a little different to handle the weight and pressure vessel orientation. Notably, the TOG Inc ship-based concept is designed to easily convert a container ship into a gas carrier.

Figure 2 below is a picture of a TOG Inc prototype type-4 pressure vessel being wound with high strength fiberglass, supplied by a major industry leader.

Figure 2: Winding of Prototype Type-4 Pressure Vessel

(c) Barge Application:

Both the carbon fiber and fiberglass pressure vessel systems can be used with marine barges, however the carbon fiber system may be more practical due to its light weight.

5. Type-4 Pressure Vessel:

Type-4 FRP pressure vessels were originally developed for the aerospace and national defense industries. Over the past two decades, FRP pressure vessels have made major inroads into the domestic marketplace, mostly as CNG fuel storage pressure vessels in the natural gas vehicle (NGV) industry. To date, more than a hundred thousand type-4 pressure vessels have been installed on natural gas fueled vehicles. Many CNG fueled busses use type-4 pressure vessels. In over a decade of use, there has never been a recorded failure of a type-4 pressure vessel.

Most type-4 pressure vessels use a HDPE liner. When fitted with metallic polar port bosses, the liner is used as a mandrel to wind-on continuous filament fibers (usually epoxy-impregnated) in very specific helical and circumferential patterns. The result is a high-strength but light-weight pressure vessel. Due to the light-weight nature of type-4 pressure vessels, they are well suited for the bulk transport of compressed natural gas. They are also suitable for hydrogen or CO2 storage and transport.