New DATUM-C Electric Motor-Driven Compressor Provides Quiet, Emission-Free Solution For Natural Gas Pipeline Applications...continued An Idea Whose Time Had Come While the natural gas pipeline industry was at one time largely limited to rural areas, in recent decades the ever expanding network of pipes and stations have become commonplace in high-population centers. As a result, gas providers have had to balance the demands of a reliable supply of natural gas, with the environmental and aesthetic concerns of their neighbors. These companies have continually sought new and innovative ways to reduce noise and emissions from their pipeline operations.  Originally, the proliferation of pipeline stations in remote areas required equipment that operated on the natural gas supply, and was not reliant on electric power. “Now with far more pipelines and stations, electric power is more readily available,” Miller said. “And many industrial users can negotiate their own costs for electricity, so the electric motor-driven compressor is more practical than it ever was before.”  The D-R DATUM-C compressor has a number of design features that make it uniquely suited to today’s natural gas pipeline installations.  The inline piping flanges of the DATUM-C allows the entire compressor to be installed directly into the line in both indoor or outdoor locations, greatly reducing infrastructure costs for new installations, as well as installation costs for retrofit applications. The small footprint – approximately 8-feet by 12-feet (2.44 x 3.66 m) – and modular design also make installation and maintenance easier.  For pipeline applications, the DATUM-C is designed with a single-stage impeller for an inlet flow of 600 mmscfd, and inlet pressure of 45 bar (650 psig) at 60 to 80 degrees Fahrenheit (15 to 26 degrees Celsius). The discharge pressure is 80 bar (1,160 psig). A second generation DATUM-C design is already in development with up to five impellers for higher pressure requirements. “Most pipelines are operating at pressures of 69 to 83 bar (1,100 to 1,200 psig),” Miller noted. “But some companies are planning new pipelines at pressures up to 172 bar (2,500 psig) to transmit more gas in a given diameter. The new DATUM-C will be able to meet those requirements, as well.” Magnetic Bearings Help Make It Green One of the most significant design features of the DATUM-C is the use of magnetic bearings. While magnetic bearings have been around for many years, previous systems were reliant on older analog control systems, making the bearings difficult to tune and adjust, according to Miller. “Previously, the magnetic bearing control system was designed, built, and tuned on the test stand, but the only way you could adjust it was to change the resistors and capacitors. Then if something changed in the field, you had to do it all over again, making it very difficult to manage, as well as time consuming and expensive. But with today’s digital controls, the computer based algorithms make tuning very simple and quick. Now that operators have become more comfortable with the advanced, Windows-based digital controls, magnetic bearings will continue to gain even wider acceptance.”  D-R has sold other compression systems with magnetic bearings, including a major pipeline station in Pennsylvania that has been running for three years. “It’s been a very reliable machine for them,” Miller said.  Because of the magnetic bearings, there is no need for an oil lubrication system, oil film seals, or dry gas seals. “The unit is a completely closed system,” Miller stated. “With no gas turbine or gear box, the entire system produces no on-site emissions, and is extremely quiet. So it is very environmentally friendly.” The DATUM-C provides variable speed operation, and the unit can remain pressurized during shutdowns.  According to Miller the new DATUM-C compressor is already drawing favorable response from pipeline clients, and additional frame sizes are planned. “Because of the scalability features of DATUM, we can develop an entire family units in the 5 MW to 20 MW range to cover the entire scope of pipeline requirements.“  DATUM-C represents a new concept in pipeline compression – one that addresses the reliability, performance, installation cost, and environmental concerns of today’s pipeline operators.