There are many industrial processes wherein large volumes of steam emissions are generated at the process site, in which steam escapes into the surrounding air space and thence is removed by fan exhausting to the atmosphere. The resultant condensation above the plant roof is sometimes troublesome. Furthermore, the heat energy represented by the escaping steam is considerable and given the current trends resulting in extremely high energy costs, such loss of energy represents a considerable cost.
If the heat energy could be employed to offset the energy demands somewhere else in the plant, considerable cost savings could be realized.
Such a situation is found in pretreatment plants for the treatment of automotive car bodies prior to the application of paint finishes in production finishing operations.
Such pretreatment plants typically take the form of a long in-plant tunnel or casing through which car bodies or other items to be treated are suspended from an overhead chain conveyor having carrier hooks extending through a slotted opening on top of the casing. The pretreatment typically involves the spray treatment of relatively high temperature sprays containing various chemicals for preparation of the surfaces to be painted. These liquids are usually water solutions and large volumes of steam emissions are produced by the spraying operation. The car bodies thence progress to a final rinsing spray just prior to exiting from the pretreatment plant. The large volumes of steam emissions have a tendency to pass out through the tunnel at either end thereof into the plant space.
Accordingly, conventionally there is provided air seals with air jets preventing the steam from passing out through the entrance and exit sections. An exhaust fan exhausts the air space within the pretreatment plant to the atmosphere exhausting the steam emissions over the plant roof.
The overhead slot for the conveyor carriers represent a potential leak point for the steam emissions. Conventionally, an air jet arrangement is also employed along the slot to preclude the exiting of steam into the surrounding plant area.
Also, certain wiper-seal arrangements have been employed towards this same end.
Thus, the considerable heat energy of the steam is entirely lost from the process, as is the water condensate.
Accordingly, it is an object of the present invention to provide a method and apparatus for both sealing a space within which steam is released such as to preclude the escape of steam emissions into the surrounding areas and also to recover the heat energy of the steam.