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Multi-Pump Oil Pumping Station Provides Economical Solution
The Qarun Petroleum Company of Cairo had a requirement to pump crude oil from its drill site to a storage distribution network as part of its expansion of oil production in the deserts of Egypt. The plan included construction of a new onshore eight inch by six inch telescopic pipeline 27 miles long to transport crude oil from its Yomna Storage location to the Karama Central Processing facilities in western Egypt. We designed, developed and manufactured four crude oil pumping stations needed to boost the oil through the telescopic pipelines utilizing an electric motor-driven series of three pumps per station.
Our solution was the integration of multiple pumps on a single platform. Two pumps are required to meet the boost requirement, while the third in the series serves as a back-up during routine maintenance and any unexpected downtime. The use of multiple pump/motor combinations provides an economical means of transferring the crude oil between various locations. Each pump was of a compact design allowing for reduced horse power electric motors. Mounting multiple pumps on a single platform increased the volume of oil that can be transferred. Each skid contained motorized screw pumps, lubrication systems, large diameter piping, electronic control cabinets and complete instrumentation.
Pumping Station Skid
To accommodate the four 1,000 gallon storage tanks, a separate 40-foot skidded pumping station was built for each tank. To meet the design specifications, we engineered a solution that would fit into a standard dry-cargo shipping container. The four 40-foot units were built in Northborough utilizing computerized design software. The multiple-pump configuration consisted of three pump/motor combinations working in parallel. Each pump draws oil from a common supply header and transfers the oil to a common discharge header. The pump/motor combinations operate as separate units; each with its own electrical controls and protective devices. Redundant pressure transmitters insure that the oil flow is continuously monitored and that the precision-ground screw pumps are protected from damage. Vibration transmitters located on each pump monitor the status of the pump end bearings.
Closed-loop lubrication pumps provide the necessary lubricating oil for the screw pump end bearings. The lubricating oil is maintained at the proper viscosity and temperature by integral heating, cooling and filtration systems. A pump system consists of a lubrication unit and its associated screw pump and motor combination. System or component failures within a lubrication pump system resulting in the complete shutdown of the lubrication system will automatically initiate an associated Main Pump shutdown. Gate and ball valves monitored by switches are used to isolate each pump unit from the rest of the system. Any combination of pumps may be on or off line without impeding oil flow from other pumps.
Oil to be transferred by the pump platform is filtered through a basket strainer system attached to the suction header. Two strainers provide the necessary filtration of the fluid, and manually operated butterfly valves control the fluid flow through the strainers. The efficiency of the strainers is monitored by two Differential Pressure Sensors, with the differential pressure being displayed on the HMI/Touch-Screen. Strainer efficiency and oil flow is reduced as the strainers accumulate debris. The strainers may be “cleaned” or back flushed by opening and closing the appropriate gate valves built into the basket strainer system. The pressure value that triggers a “Warning” message on the HMI screen does not cause the pump system to shut down or to be disabled.
A pump system is defined as a lubrication unit, the associated main pump and a manually configured “bypass” valve. When the bypass valve is open the fluid flow from the main pump flows to the low pressure return manifold. Each pump system incorporates a pressure operated safety relief valve. If a high pressure condition develops on the discharge side of the main pump the relief valve opens and fluid flows to the return manifold. A check valve on the discharge side of the pump prevents reverse fluid flow from the discharge header to the main pump. When the bypass valve is closed fluid flows from the main pump through the check valve to the main discharge header. There are redundant sets of pressure sensors on the suction and discharge sides of the main pump.
Electronic Control Cabinet
Each pump system includes a stack-light assembly mounted on top of the MCC (Motor Control Cabinet) enclosure. The stack-light for pump system “A” is located to the left side of the MCC enclosure when viewing the enclosure from the two door side. Pump system “B” is in the center of the enclosure and system “C” is to the right. During operation the status of a pump system is indicated by indicator lamps. Green indicators illuminate when a “Main” pump is operating. Amber or yellow “Warning” indicators illuminate if a condition exist which the technician should be aware of. A typical “warning” could be “High Differential Pressure” at the filter/strainer assembly. Red indicators represent “Alarm” conditions which typically initiate a shutdown event. The red indicator will illuminate if a situation develops where an alarm and a warning exist at the same time. It is possible for a green and amber indicator to illuminate at the same time if for instance a main pump is running and high differential pressure is detected at the strainer assembly.
The LCC (Local Control Cabinet) enclosure is also equipped with a stack-light assembly consisting of green, amber and red indicator lights. The colors are indicative of the over-all status of the three pump systems on the skid. A green light will illuminate on the LCC cabinet when there are no existing warnings or alarms within the three pump systems. Amber represents warning conditions and red is displayed to represent alarms. Alarm conditions have a higher priority than warning messages. The controller will illuminate the LCC enclosure Red stack-light indicator if a warning and alarm condition exist at the same time.