Abstract

Horizontal Pumping System (HPS) is a surface application of a Multistage Centrifugal Pump originally designed for submersible service. HPS's are highly flexible in operation. Suction pressures can vary from 50 to 2500 PSI and the standard design discharge pressure can be up to 5000PSI with standard design. Variable flow rates can be achieved with a flow control valve without changing the operating speed, which eliminates the expensive Variable Speed Controller. Re-circulation lines and isolation valves are not required so the required piping is very simple compared to Positive Displacement (PD) pump installations. Unlike PD pumps, HPS can be deadheaded for a short time without damage. If a line plugs or a valve closes there is little danger of having the line or pump burst. HPS can be started against full system back pressure or with no back pressure at all. HPS's operate very quietly with very low line vibrations, as the HPS's are not generating fluid pulsation typical to PD installations. It can be easily designed as a Zero Emission system for operation in hazardous fluids with double seals with blocking fluids and control systems to ensure that the produced fluid will not escape to the environment. PLC can be easily tied into the HPS to control flow, pressure, tank level, speed, etc. Units can be run in parallel or series configuration. Heavy foundations are not required and it can be used as a portable unit. There is a significant reduction in maintenance cost, as there is little field maintenance required. Pump repair time can be as little as one day. Modular components allow for easy field retrofit. Due to the simple design of HPS, it can be operated remotely. We will present in this paper a very challenging HPS application as a Water Injection Line Booster with Pengrowth Corporation in Judy Creek, Alberta. This unit was designed to boost pipeline pressure on average from 13.5Mpa (1958PSIg) to 17.2Mpa (2500PSIg) at the flow rate of 5900 m3d (1080gpm). The intake seal utilized in this design is very special in nature as this application presents a challenge on several fronts. The process fluid is slightly sour water at about 65Co with suspended solids that are abrasive, but the challenge is that the suction pressure is dynamically variable between 11MPa (1595PSIg) to 15MPa (2175PSIg). The engineers from the seal supplier came up with a solution to answer all of these concerns with a promise to make it work. The seal selected was a back to back double seal with a highpressure lubricator. The inboard seal sees a differential pressure of about 690kPa (100PSIg) (barrier fluid pressure 100PSIg above suction pressure) and the outboard seal sees full barrier fluid pressure, up to 15.7Mpa (2275PSIg). A very unique design feature of the inboard seal is that it is able to handle a full reverse pressure either from the barrier or product sides with a 0 PSIG differential. The high-pressure barrier fluid lubrication unit was designed to maintain the pressure of the mechanical seal barrier fluid above the fluctuating pump intake pressure.

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