This next generation of slow-speed compression should attain 95% efficiency, a three-year valve life, and expanded turndown. Retrofit technologies that address the challenges of slow-speed integral compression are: (1) optimum turndown using a combination of speed and clearance with single-acting operation as a last resort (2) if single-acting is required, implement infinite length nozzles to address nozzle pulsation and tunable side branch absorbers for 1x lateral pulsations and (3) advanced valves, either the semi-active plate valve or the passive rotary valve, to extend valve life to three years with half the pressure drop. The goal of this advanced reciprocating compression program is to develop the technology for both high speed and low speed compression that will expand unit flexibility, increase thermal efficiency, and increase reliability and integrity. The thermal efficiency is 10% to 15% lower than slow-speed equipment with the best performance in the 75% to 80% range. Valve life is even shorter than for slow speeds and can be on the order of a few months. The shortened nozzles result in mechanical coupling with the cylinder, thereby, causing increased vibration due to the cylinder stretch mode. To shift nozzle pulsation to higher orders, nozzles are shortened, and to more ยป dampen the amplitudes, orifices are added. The major challenges for high-speed machines are: cylinder nozzle pulsations, mechanical vibrations due to cylinder stretch, short valve life, and low thermal performance. In the better performers, the losses are about evenly split between installation losses and valve losses. The major cause for this large disparity is due to installation losses in the pulsation control system. While the best performing units in the fleet exhibit thermal efficiencies between 90% and 92%, the low performers are running down to 50% with the mean at about 80%. In an attempt to increase flexibility, many operators are choosing to single-act cylinders, which are causing reduced reliability and integrity. The major challenges with the fleet of slow-speed integral machines are: limited flexibility and a large range in performance. Most new reciprocating compression is and will be large, high-speed separable units. The current fleet of installed reciprocating compression is primarily slow-speed integral machines. To meet these challenges, the industry requires improved choices in gas compression to address new construction and enhancement of the currently installed infrastructure. ![]() natural gas pipeline industry is facing the twin challenges of increased flexibility and capacity expansion.
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