(69d) Process-Utility Interaction Analysis for a True Energy Saving Value Determination

This paper shares the experience of Saudi Aramco's energy assessment team in finding a true energy saving potential from one of the Aramco's oil and gas plants. It involves a comprehensive energy assessment of both the process and utility section of the plant simultaneously. In the case of process energy saving assessment, pinch analysis together with other process improvement tools (e.g. process simulation analysis) is normally used to identify the energy saving opportunities. During this analysis, no value of energy saving ($/year) is determined but rather the analysis only focuses on the amount of savings in both heating and cooling loads. During this stage too, the team highlights the pros and cons of such energy saving initiatives, which includes the proposed project cost estimates, operability aspects and safety considerations.

In a separate task, the utility team uses an in-house utility modeling tool to assess energy performance of the existing utility system. The advantage of having such a model is not only for its ability to optimize the existing utility performance but also the ability to ?link' or interact with our energy saving findings from the process section. For example, the team can then see clearly the full impact of reducing the heating load in the process on the performance of the utility system itself. Hence, this allows the true energy saving value be determined from the overall performance of the utility system.

Once the true energy saving potential has been determined for each of the identified opportunities, the proposed projects can then be prioritized according to the common decision criteria, like economics, operability and safety. A case study from one of the Saudi Aramco's NGL fractionation facilities will be used to demonstrate the approach highlighted in this paper.