Patent Application
20130069319
The present invention relates to shaft seals for rotating mechanical equipment.
Shaft seals are employed to prevent or minimize leakage around rotating shafts on a wide variety of machines. For example, the majority of centrifugal slurry pumps in heavy duty slurry services throughout the mining industries feature a packed stuffing box type shaft seal. Currently, this seal must be adjusted manually in regular and frequent intervals to function properly.
Referring to
In order for this type of arrangement to work properly, a minimum amount of gland water flow is required. The amount of flow can be adjusted by manually tightening or loosening the packing gland adjusting nuts 126, 126A with a suitable wrench. This will adjust the amount of compression on the soft packing material and thus vary the amount of water that will be allowed to leak from the shaft seal. Depending on the type of service and the amount of gland water pressure required, frequent adjustments must be made to maintain proper gland water flow. To perform this adjustment, the pump will have to be shut down and electrically locked out.
In the past, adjustments were made by maintenance personnel while the pumps were operating. More stringent safety regulations imposed on industry have made this common practice impossible due to the close proximity of the shaft seal to the rotating pump shaft. As the pump shaft now has to be completely guarded, ready access to the stuffing box is no longer available to adjust the packing gland of the shaft seal. Instead, the pumps must be shut down and electrically locked out before any work can commence. Any safety guards that are mounted in place will have to be removed. After the adjustment is made, all guards will have to be reinstalled and the pumps will have to be restarted to check for proper sealing performance. This down time is very costly in terms of lost production for the operations, especially on multi-pump pipeline installations. As a result, proper maintenance is often neglected, leading to shorter equipment operating life and excessive repair costs.
In view of the foregoing, it is an object of the present invention to provide a way of remotely adjusting the shaft seal is needed while the pumps remain in operation with all safety equipment and guards in place. According to an embodiment of the present invention, a shaft seal arrangement includes a stuffing box defining a stuffing box central shaft opening extending around a shaft axis, packing arranged in the stuffing box around the central shaft opening, a packing gland defining a packing gland central shaft opening, and at least one adjuster assembly remotely operable to vary an engagement force between the packing gland and the packing. The adjuster assembly can be arranged around a packing gland stud and include an adjuster piston that is hydraulically operable to advance against the packing gland to vary the engagement force.
According to an aspect of the present invention, a stud-mounted adjuster assembly includes an adjuster body defining a stud passage and a piston cavity, the stud passage surrounding a stud axis through which a stud is accommodatable so as to extend through the outer body, and an adjuster piston movably arranged in the piston cavity and projectable therefrom in the direction of the stud axis. The adjuster piston and cavity can encircle the stud passage and be advanced against the packing gland around the stud.
According to a method aspect, a method of operating a shaft seal arrangement for rotating machinery includes remotely operating an adjuster assembly to vary an engagement force between a packing gland and packing of the shaft seal arrangement. Advantageously, the adjuster assembly is operated while the rotating machinery remains in operation.
These and other objects, aspects and advantages of the present invention will be better appreciated in view of the drawings and following detailed description of a preferred embodiment.
Referring to
A remote mounted motive fluid dispenser is permanently connected via suitable hydraulic hoses to a port 32 in an adjuster body 33 of each adjuster assembly 30. The amount of shaft seal water flow can now be adjusted while the pump remains in operation with all safety guards in place by introducing a motive fluid under pressure into the port 32, thus advancing an annular piston 34 within the adjuster assembly 30. The piston 34 in turn advances the packing gland 18 to increase the amount of load on the packing 16 and decrease the amount of water that will be allowed to leak from the seal 10.
The adjuster body 33 can includes concentric outer and inner components 40, 42 between which a piston cavity 44 for the annular piston 34 is defined, surrounding the passage 46 for the stud 20 extending through the inner component. Alternately, the adjuster body 33 can be manufactured as a single piece, with the piston cavity 44 and stud passage 46 machined or otherwise formed therein. The adjuster body 33 can threadingly engage the stud 20.
It will be appreciated from the foregoing, that a shaft seal arrangement 10 including the adjuster assemblies 30 of the present invention allow adjustments to be made while the pump remains in operation, without requiring the removal of any guards. Moreover, because the pump remains in operation, an instant visual check can be performed to determine whether the proper level of adjustment had been made. Additionally, adjuster assemblies 30 according to the present invention can be easily retrofit into existing shaft seal arrangements 10—for instance arrangements.
In general, the foregoing description is provided for exemplary and illustrative purposes; the present invention is not necessarily limited thereto. Rather, those skilled in the art will appreciate that additional modifications, as well as adaptations for particular circumstances, will fall within the scope of the invention as herein shown and described and of the claims appended hereto.
This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/536,136, filed on Sep. 19, 2011, the contents of which are herein incorporated by reference in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61536136 | Sep 2011 | US |
