Optimization of Compressed Air Systems in Gas Processing Industry
Authors: Nambakkam Harindranath , Al Ghailani Mi , Sajjad Saqib , Al Jenaibi Eisa , Al Sayegh Farah 
Published: November 2019

The main objective is a comprehensive and comparative energy study, for optimization of instrument & utility air systems installed at ADNOC Gas Processing multiple sites, comprising step-by step in-depth review of compressed air generation, distribution and utilization. It includes identification of potential opportunities for energy savings along with suggesting ways & means for reducing energy losses. The scope encompasses extensive data collection, review of specific energy consumption & deviations from design and detailed analysis. Energy studies are usually targeted to achieve energy saving potential in the operations line. The key element of these kind of studies is site visits and discussions with the site personnel connected with Operations and Maintenance.

The study was conducted on all sites of the company covering all major air compressors to examine the assessment of free air delivered (output of compressors), estimate the specific energy consumption and quantify the leakages of the compressed air in the network. It included analysis of pressure drop in the system, loading and unloading patterns and the effectiveness of intercooler and after coolers. The optimization study resulted in identifying operational features of compressors such as flow and pressure controls, energy conservation measures by user area analysis, reducing operating and discharge pressure.

This study has resulted in several potential energy saving possibilities that shall be taken into account such as reducing specific power consumption, repairing compressed air leakage, reducing compressed air pressure settings, installing high efficiency motors wherever applicable, installing capacitor banks to improve power factor and using outside cool air intake. Application of VFD was tried but the techno economics were not supporting. Some of these saving potentials do not require large investment but can lead to 15 to 20 percent savings in energy consumption that indicates that it should be given priority and in-depth study. The approach would also entail use of energy-saving retrofits and modifications to reduce the losses identified.

Interaction with operating and maintenance personnel during study has indicated that staff recognition & rewards significantly contribute towards boosting the realization of energy saving opportunities. These type of studies lead not only to energy savings but also helps in overall up keeping of Air compressors and its associated equipment.

The study successfully quantified the gap in specific power consumption from design. Major observation in operation was loss of energy through system bleed off valves. Study also indicated opportunity of additional energy savings by periodic maintenance of compressors namely changing internals, overhauling, cleaning of inter and aftercoolers, deploying suitable control logics and using efficient intake filters. Yearly leakage test to ascertain losses in the system was recommended to curb the losses and improve energy performance.