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VWU Series Vaporizers:
Water heated shell and tube vaporizers. Hot water from an outside source circulates through the shell, cryogen is vaporized through the tubes.
Water heated vaporizers are similar in appearance to the direct steam vaporizers and fall somewhat between the VSU and VSSU with regard to vaporizing efficiency per unit of surface area. Performance is relative to the available water temperature.
They are extremely simple to operate. The VWU series vaporizer can be used either as part of a water circulating vaporizing system (WCV) or as a stand-alone vaporizer where the customer provides the water, usually as part of an existing cooling water stream. The vaporizer is able to operate in either vertical or horizontal configuration. Capacity is dependent upon shell side water temperatures. Water circulating vaporizers are ideal when the gas outlet temperature is sensitive and must not be elevated going to the process.
The vaporizer is designed such that the flow rate of the available water is matched to the required maximum vaporization heat load. This ensures full vaporization of the incoming cryogen with an acceptable gas outlet temperature. The water flow rate becomes a fixed parameter drastically simplifying the controls necessary to operate the vaporizer. If the cryogen flow diminishes full vaporization is still achieved, but the gas outlet temperature approaches closer to the water temperature, but still within an acceptable value for the process. It cannot be elevated above the temperature of the water. In this mode of operation the vaporizer "self controls" requiring only a minimum of additional simple controls.
Individual heat exchangers are commonly used as a local product vaporizer, and also for disposal vaporizers for air plants. They can be utilized as part of a large WCV system, these units are frequently used in back-up service.
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