Automated solution for a fixed displacement vane pump helps save energy during tooling/logging while drill testing.
by Brian Bennett & Jack Creamer, Schneider Electric
March 27, 2013

International oil service companies with $18 billion in revenue in 2010 understand the importance of energy saving resources. In 2011, an oil services company requested bids for a pump to use for its downhole tooling/logging while drilling testing. The industry standard for this type application is a variable displacement piston pump, which can be a large, costly and mechanical-based solution that requires a long lead time.

Ed Martell, vice president of systems for Romeo Engineering, in Fort Worth, Texas, envisioned something quite different. Martell had dreamed of a more innovative solution but had not made his dream a reality. He wanted to reduce the cost of the standard hydraulic components and create an automated solution that was smaller, less costly and available in a shorter time period. Most important, he wanted to develop a solution that was more energy efficient but just as effective as a variable displacement piston pump.

Solutions Outside the Norm

With the help of an energy management company that offers integrated solutions, the Romeo engineering team, led by Martell, developed an automated solution for a fixed displacement vane pump—using a drive, a programmable logic controller (PLC) and pressure transducers—that changes pressure by changing the rpm of the motor.

Unlike the variable displacement piston pump, with which the motor runs at the nameplate rating, the drive solution on the fixed displacement vane pump soft starts the motor. Then it only generates the required fluid power based on the pressure setting and the flow requirements.

In fact, Martell reported that the fixed displacement vane pumps have run at as low as 12 percent of power at the maximum pressure of 3,500 psi, an 88 percent savings for a 150-horsepower motor. In the end, Romeo was able to provide the oil services company with a solution that was as responsive as the industry standard but with significant energy savings.

From the beginning, Romeo planned a green solution—one that used less water, much less electricity and required a much lower electrical demand cycle because the flow and pressure requirements were managed more efficiently.

Because the solution was automated, it gave the oil services company a window into the health and welfare of the solution. The PLC sends data to a human machine interface (HMI) with which operators can manage many variables—including the rpm of the motor, to dial in the gallons per minute; the percent of energy that the motor uses for each pressure setting; the temperature of the oil in the intake; the pressures of the return manifold; and the pressure and temperature in the heat exchanger. The system brings up an alarm if conditions exist outside of the set parameters.

Additional Benefits

While the energy-saving benefits of the fixed displacement vane pumps certainly were considerable, other benefits were also important—including a shorter lead time, much lower replacement costs and a smaller size. Because a fixed displacement vane pump is a commoditized solution, it is available from many manufacturers worldwide. OEMs can receive the solution in two to three weeks. A variable displacement piston pump can take up to 16 weeks to obtain.

The standard components of the former solution allow OEMs to respond more quickly to customer requests and speed the time to market. Additionally, the replacement costs for a fixed displacement vane pump are about 10 times less than that of a variable displacement piston pump.

“Not only are the replacement cost magnitudes less for a fixed displacement pump, but it is also a more rugged and reliable solution,” Martell said. “Pressure-compensated piston pumps are especially susceptible to contamination in the working fluid that can result in piston or swash plate damage. We were able to reduce the component cost and move the same amount of money into the drive and control portion of the solution, which doesn’t need to be replaced often.”

The size of the fixed displacement vane pump is smaller than the industry standard piston pump with the same flow rating—a huge benefit because space is always at a premium. Fewer plumbing connections and a lower total part count are responsible for the smaller size.