Evaluation of variable speed drives to improve energy efficiency and reduce gas emissions: Case study

Variable speed drives are the most promising technique to reduce electric motors energy consumption. This paper discusses energy savings achieved by installing variable speed drives to control rotating equipment motors such as pumps, compressors, blowers, and fans in oil processing facilities. In addition to energy savings, variable speed drives will improve overall equipment efficiency, increase reliability, and reduce greenhouse gases (GHG) emissions. An Energy audit was performed on a case study to investigate energy consumption for all electric motors. Technical and operational constraints for installing and operating variable speed drives have been discussed. Installation requires adjustments in operation schedules and parameters to allow reducing energy consumption. The case study has illustrated how to calculate energy savings for Pipelines, air coolers, air blowers for furnaces, pumps with variable flow rates and reciprocating compressing systems. Variable speed drives were technically and economically accepted in air blowers, fans, and pumps. Energy consumption and greenhouse gases have been reduced by 67%, Payback period for the whole project was less than 1 year. Meanwhile, it was not valid for reciprocating compressors as the Payback period was 6.2 years.