Based in North Dakota, Industrial Equipment Sales & Service (IESS) has been providing high-quality pumps, parts, and services to the oil and gas industry since 1999. IESS was contacted in 2014 by a sand and gravel wash plant that was trying to find a more economical way to recover the sand fines that they had previously been lost in the process of cleaning aggregate. Sand fines, which are essentially granular sedimentary particulate, are typically required for the mixing of a high-grade concrete commonly used in oilfield applications.
The sand and gravel wash plant initially tried using a 2-inch self-priming centrifugal pump from a well-known manufacturer, but due to the high abrasiveness of the process slurry, the 2-inch self-priming centrifugal pump failed after only 245 hours of operation. After replacing two self-priming centrifugal pumps in the first three months of starting the sand fine reclamation process, the wash plant reached out to the industrial specialists at IESS to discuss a more cost effective solution.
The sand and gravel wash plant operates on a seasonal basis, working about 6 to 7 months each year. During this time, their system runs an average of 10 hours per day, five days each week. They had initially set up the sand fine reclamation process to send the sand slurry, via gravity, directly to the self-priming centrifugal pump from the aggregate shaker and wash unit. The self-priming centrifugal pump then transferred the fine clay and sand slurry to another process stage to recover the sand fines, rather than sending the material to a settling pond.
In reviewing the plant’s sand fine reclamation process, it became clear to the IESS support specialist that two things needed to happen to make the process more economically advantageous: 1) the process needed to be re-organized to be more efficient; and 2) the wash plant needed a dewatering pump that would operate longer. The new pump needed to operate reliably for a longer period of time – much more than 245 hours before being replaced or rebuilt!
The IESS support specialist recommended the following changes: 1) allow gravity to pull the sand slurry from the aggregate shaker and wash screen into a 300-gallon container. 2) Place a submersible dewatering pump inside the 300-gallon container to transfer the slurry to a sand-recovery unit. The IESS support specialist recommended using a light-weight Submersible Dewatering Pump, BJM Model LWAE15. He recommended the LWA pump for the following reasons:
The LWA Series is specifically designed and constructed for dewatering sand, silt, coal fines, and abrasive light slurries. This application demanded a hard metal submersible dewatering pump that could handle the abrasive nature of a sandy slurry, and the LWA has a chrome iron impeller and wear plate. Chrome iron counters the effects of erosion, helping to maintain pump performance and improve overall pump life by providing higher endurance for abrasive applications. Due to its construction, the LWA hard metal pump would easily outlast a rubber-lined or cast iron pump.
The LWA Series Submersible Dewatering Pump has a hardened ductile iron volute and agitator. The built-in agitator would be perfect for stirring up the fine sand particulate with the wash water so the slurry could be efficiently transported while also maintaining the required container (or basin) volume.
The LWA’s 3,450 RPM motor (NEMA B Design) utilizes double mechanical seals, where the upper seal is comprised of carbon/ceramic and the lower seal is comprised of silicon carbide/silicon carbide. The motor is protected with Class F motor insulation and includes an auto overload switch.
The sand and gravel wash plant accepted the recommendation from IESS and installed the first LWAE15 Submersible Dewatering Pump in 2014. The LWAE15 transfers the slurry to a sand-recovery unit, delivering approximately 120 GPM (gallons per minute) at 25 TDH (Total Dynamic Head). The in-flow from the aggregate shaker and wash screen is manually regulated, staying between 80 – 100 GPM. For cooling purposes, the LWA Submersible Dewatering Pump must be fully submerged at all times. Therefore, the process slurry being discharged from the LWAE15 is also manually regulated so that a specific amount can be bypassed back into the 300-gallon container to maintain pump submersion.
While it is a fact that abrasive applications destroy pumps over time, the average run-time of the LWAE15 in this specific slurry application is significantly better than the run time of the self-priming centrifugal pumps. The LWAE15 reliably pumped the sand slurry for 800 hours (about 4 months) before having to be pulled and rebuilt. IESS received feedback from the sand and gravel wash plant that the pump-related cost of sand fine recovery is now $1.06 per hour of operation as compared to the $11.43 per hour cost when using the self-priming centrifugal pumps. The new process and BJM Pumps have made the plant’s sand fine reclamation process more economically productive.
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