Plant cooling water, seawater, once-through river water, or a closed loop water/glycol system can be used to vaporize cryogenic fluids with these units.
Water temperatures as low as 45°F (7°C) are used in Thermax designs. Since these vaporizers are generally added to an existing water system there are no additional power requirements and consequently significant energy savings. In some cases the cooling effect from vaporizing the cryogen can also be used elsewhere in the plant. Circulating water vaporizers can be used to vaporize various many cryogens and liquefied gases including nitrogen, oxygen, argon, CO2, ammonia, chlorine, LNG, ethylene and many others.
Cold Circulating Water Vaporizers use an existing water source for vaporization. Water flows on the shell side of a shell and U-tube heat exchanger. The cryogen is vaporized and superheated through a stainless steel tube bundle that is fit with proprietary vortex generators. Both the shell and tube bundle can be fabricated of exotic materials to handle the most problematic cryogens. Standard units are available for up to 10 MSCFH.
Cryo-Coils offer a compact solution to vaporization. Stainless steel Vortex Flow Vaporizer coils are fitted into a shell to provide counter current flow with a fluid (water) stream. The counter current flow increases heat transfer and reduces the required amount of surface area. These units are also used as coolers to chill temperature control unit fluids such as Syltherm and Dowtherm. Standard units are available to 6,000 lbs/hr CO2.
Indirectly Fired Water Circulating System (WCS) Vaporizers are entire skid mounted systems that combine a fuel fired water heater, a pump around loop, and a Thermax shell and tube vaporizer. Water from a packaged heater is pumped through the shell side of a Thermax vaporizer providing heat for vaporization. The cooled water is then returned to the heater. The vaporizer, equipped with Vortex Generator tubes, vaporizes and superheats the cryogen. Standard units are available up to 300 MSCF.