Qatargas Energy Efficiency Monitoring

Abdulla Al-Hajri's picture
Abdulla Al-Hajri, Surveillance Engineering Manager, Qatargas
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In LNG plants, the majority of processed gas is transformed into commercial products such as LNG, Shale gas, LPG and Gasoline. However, a small part of this processed gas is used for:

  • Internal requirements for electrical power generation
  • Process gas turbines
  • To produce different energy carriers (steam, hot oil.).

This internal energy consumption can range from 6 - 12% depending on the process used and the actual efficient use of energy.

Since 2013, Qatargas has worked with regulators on an energy efficiency monitoring tool; with its main purpose to compare the actual amount of energy consumed in the existing Qatargas assets to the design (baseline) and to identify areas of improvement of energy efficiency. This tool monitors the conversion efficiency of one form of energy (Fuel Gas) into other forms (steam and power) and how these energy carriers are efficiently utilized for process requirements.

Every quarter, Qatargas provides the regulator with fuel gas, steam, electrical and shaft power consumption, and production data at a process block level. The energy efficiency monitoring tool uses the data to determine generation and consumption performance indices which measures respectively the efficient conversion of fuel gas into power and heat and the utilization of energy in the commercial products processes.

The monitoring tool calculates performance indicators (indices) for energy consumed in the main process equipment such as:

  • Boilers
  • Gas turbines generators
  • Gas turbines driving process compressors
  • Different other energy users

These indices are calculated by comparing the generation and consumption data with representative design values. The references used for Qatargas assets are P10 winter, P50 and FP50 basis of design (ambient air at 29 C) respectively for QG1, QG2 and QG3&4. These design references have a feed gas composition similar to current actual compositions in the three assets. The reference ambient temperatures for each asset are considered when the differences between design and actual energy consumption are analyzed by Qatargas.

For the purpose of comparing different forms of energy and benchmarking with others regulator assets and JV’s; consumed and generated electrical power, steam, shaft power and fuel gas, are converted into “Qatar Reference Gas” (QRG - natural gas with a higher heating value of 1000 BTU/scf).

After consumption and production data has been submitted to the regulator, the energy efficiency report is presented to Qatargas. This report contains key indices, the potential gas savings and its breakdown to process block level (condensate stabilization, Gas treatment, LNG). Qatargas has developed a tool to extend the breakdown of potential gas savings to the equipment level to identify energy efficiency “bad actors” and initiate corrective actions to be discussed and agreed with operations.

Since the start-up of this Energy efficiency initiative, 17 reports per asset have been presented and analysed; which have contributed to the identification of a group of processes, which represents the highest energy losses and the biggest potential for energy efficiency improvement. These main energy efficiency “bad actors” are:

  • The steam system, particularly the dump condenser, deaerators and pressure letdown station.
  • The electrical power generation GTG’s and STG’s.
  • The cooling (sea water, FCW) used for process refrigeration loops.

During the last four and half years of energy efficiency reporting and analysis, the potential gas savings has been decreasing through few actions such as:

  • Hydraulic turbines utilization improvement
  • MP steam consumption reduction in the AGR’s
  • MP steam to dump condenser reduction

However, the most important achievement is the maturation of the Energy Efficiency monitoring tool itself and its ability to analyze interaction between different systems (such as Steam-Electrical-VFD’s), identify “bad actors” and quantify the potential gas saving resulting from implemented engineering solutions.

Share your insights and join the conversation: How do you think the energy efficiency monitoring tool will revolutionise projects? Leave your comment below.

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