BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
FIG. 1 is a perspective illustration of a known conical cyclone separator, having a conical vane plate located at the bottom of the lower cylindrical water outlet;
FIG. 2 is a perspective illustration of another known conical cyclone separator, similar to that shown in FIG. 1, and having a conical vane plate located at the bottom of the lower cylindrical water outlet but with a longer cylindrical portion between the upper conical portion and the conical vane plate;
FIG. 3 is a graph showing moisture carryover versus steam flow for the conical cyclone separator of FIG. 1 and the conical cyclone separator of FIG. 2;
FIG. 4 is a graph showing conical cyclone pressure drop versus steam flow for the conical cyclone separator of FIG. 1 and the conical cyclone separator of FIG. 2;
FIG. 5 is a graph showing moisture carryover versus water level for the conical cyclone separator of FIG. 1 and the conical cyclone separator of FIG. 2;
FIG. 6 is a perspective illustration of another known conical cyclone separator, wherein the steam/water inlet partially extends into the cylindrical portion, and having a conical vane plate located at the bottom of the lower cylindrical water outlet;
FIG. 7 is a perspective illustration of another known conical cyclone separator, wherein the steam/water inlet partially extends into the cylindrical portion, and having a conical vane plate located at the bottom of the lower cylindrical water outlet but with a longer cylindrical portion between the upper conical portion and the conical vane plate;
FIG. 8 is a perspective illustration of a first embodiment of the extended water level range conical cyclone separator according to the present invention, having a steam/water inlet which extends only into the conical portion, a conical vane plate, and an extension sleeve portion located below the conical vane plate whereby the conical vane plate is located at an intermediate location between the upper conical portion and the bottom of the lower cylindrical water outlet;
FIG. 9 is a perspective illustration of a second embodiment of the extended water level range conical cyclone separator according to the present invention, having a steam/water inlet which partially extends into the cylindrical portion, a conical vane plate, and an extension sleeve portion located below the conical vane plate whereby the conical vane plate is located at an intermediate location between the upper conical portion and the bottom of the lower cylindrical water outlet; and
FIG. 10 is a cross-sectional view of a conventional steam drum, in this case employing three rows of cyclone separators, to which the improved steam/water conical cyclone separator according to the present invention could be applied.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to the drawings generally, wherein like reference numerals designate the same or functionally similar elements throughout the several drawings, and to FIG. 8 in particular, there is illustrated a first embodiment of the extended water level range steam/water conical cyclone separator, generally designated 50. The present invention incorporates the use of an open bottom cylindrical extension sleeve portion 19 that is attached to the current extended length cyclone separators having the lower cylindrical portion 14′, such as those illustrated in FIGS. 2 and 7. In this design, the conical vane plate 19 will remain at the normal location that was established for the current extended length cyclone separators (FIG. 2, and FIG. 7). By this positioning of the conical vane plate 18 with respect to the extension sleeve portion 19, the conical vane plate is located at an intermediate location between the upper conical portion 12 and the bottom of the lower cylindrical portion 14′, which is now the open bottom portion of the extension sleeve 19. The open bottom extension sleeve 19 allows the new separator's length to be increased while maintaining the performance of the separator designs, 20, 40. The extension sleeve 19 increases the overall length of the separator 50 so that the steam drum's operating water level range can be extended to the maximum high and low variations that are functions of the size of the steam drum. Therefore, for HRSG, radiant syngas cooler or any other boiler applications, the water holding capacity of the steam drum can be maximized.
Graphical views showing the new extended length cyclone separator are shown in FIG. 8, (with 6 inch extension) and in FIG. 9, separator 60, (with 6 inch extension). These new steam/water conical cyclone separators 50, 60 maintain the conical vane plate 18 at the same location as the aforementioned separators, 20, 40, respectively, and have an overall length of about 34 inches. By locating the conical vane plate 18 at these locations, the pressure drop characteristics that the conical vane plate 18 provides to the separator 50, 60 helps to maintain the performance and separation efficiency of the separator 50, 60 across the larger water level range of the steam drum. The cylindrical extension sleeve 19 that is used below the conical vane plate 18 could also incorporate a few small holes or apertures 70 (schematically indicated in FIGS. 8 and 9) so that the pressure drop characteristics of the conical vane plate 18 are maintained for very large diameter steam drums (greater than 70 inches ID) where the water level hydrostatic head does not influence the pressure drop characteristics across the conical vane plate 18. Preferably a minimum of four holes 70 that are about ¼″ to no larger than about ½″ would be evenly distributed around the upper portion of the cyclone separator extension sleeve 19, but below the location of the conical vane plate 18. In cases where a long (e.g., greater than 1 ft.) cylindrical cyclone separator extension sleeve 19 is used, these holes 70 would also be spaced along the length of the cylindrical cyclone separator extension sleeve 19 spaced at about even intervals and no farther than 6″ apart.
The incorporation of the holes 70 in the conical cyclone separator extension portion 19 helps to reduce the pressure differential across the cyclone separator conical vane plate 18. When the cyclone separator 50, 60 is experiencing either very high or very low water levels in the steam drum, these holes 70 help to reduce the hydrostatic pressure head at the conical cyclone separator vane plate 18. This feature allows the conical cyclone separator 50, 60 to perform with similar performance as a cyclone separator without the extension portion 19.
FIG. 10 illustrates a cross-sectional view of a conventional steam drum, taken from the aforementioned Steam 41st reference text, in this case employing three rows of cyclone separators, to which the improved steam/water conical cyclone separator according to the present invention could be applied. As will be appreciated by those skilled in the art, the drum inside diameter would be increased to accommodate the extended length of the steam/water conical cyclone separator 50, 60 of the invention.
The present invention has several advantages, including the benefit that its use will result in a shorter length drum for applications that require longer than normal water holding times. For special applications, a customer could require that the drum contain a set amount of water for special transient or load restraints. This amount of water is required to protect the boiler from tube overheating during a transient and/or special operational event where the feedwater system fails to provide sufficient water (such as a black plant, load excursion, etc.). In sizing the steam drum for a large amount of water inventory, a larger diameter drum with a short length could be more economical than a smaller diameter drum with a longer length; therefore the benefits of this new idea are important for maintaining steam drum performance while increasing the water level range and water level inventory of the drum.
The improved steam/water conical cyclone separator according to the present invention maintains the performance and pressure drop characteristics of the current cyclone separator designs while increasing the water level range and water holding capacity of the steam drum. The only alternative to meet the water holding capacity for a specific boiler design would be to use a normal size steam drum that is much longer than the steam drum that could be designed utilizing the extended range conical cyclone separator.
According to the present invention, thus a relatively simple modification yields substantially improved results in an unexpected manner.
While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles. For example, the present invention can be applied to new steam drum construction or to the repair, replacement and modification or retrofitting of existing steam drums, provided sufficient drum internal diameter is available. Further, certain features of the invention may be advantageously employed without a corresponding use of other features. Accordingly, all such variations and modifications of the present invention will be readily apparent to those skilled in the art and the present invention is intended to cover in the appended claims all such modifications and equivalents covered by the scope of the following claims.
Patent Application
20080069646
