Hydraulic Compression Take-Up Device
Publication Date: 2003-Jun-20
The IP.com Prior Art Database
During assembly, the stages of an Electric Submersible Pumps (ESP) are placed in compression by tightening the top bearing against the diffuser stack. The compressive force prevents the diffuser stack from spinning and maintains a stage-to-stage seal between each diffuser in the stack. During installation and/or operation, the initial compressive force can decrease, or in come cases, cease to exist due to stretch of the housing due to the inlet-to-discharge pressure differential and the weight of the motor and seal that is supported by the pump housing. The compressive force can also decrease due to elongation of the housing due to thermal growth and a relaxing of the diffuser stack height as it creeps due to the compressive load and takes a permanent set. My invention consists of a hydraulically actuated take-up device that utilizes the ESP's discharge pressure. The discharge pressure acts on two opposing pistons that continue to supply a compressive force even if the initial compression ceases to exist or if a gap opens between the diffuser and top bearing. The compressive force developed is directly proportional to the discharge pressure. The application for my invention is large pumps (562-Sereies and higher) with deep settings and high down hole temperatures. Loss of compression resulting in diffuser spinning is typically a problem with longer, i.e. high stage count pumps, and the problem is exacerbated by thermal growth of the housing due to high down hole temperatures. My invention directly addresses the problem of spinning diffusers in large pumps with high stage counts and high temperatures. The amount of compressive force that can be developed by my invention increases with discharge pressure which increases as stage count increases. My invention is unaffected by temperature. Thus, my invention becomes more effective as the conditions that cause diffuser spinning worsen.