Even with the recent reduction in energy prices, energy remains the largest cost after feedstocks for most process plants. Reducing fuel usage is also the preferred way to reduce emission as required by the steadily more stringent Greenhouse Gas Regulations. There are many low cost automation investments that can have significant energy and emissions savings. Identifying and economically justifying the automation investments that will reduce energy and emissions is the subject of this presentation.
Doug’s objective for the presentation was to help people recognize the many ways that automation, advanced automation and asset management can save energy and reduce emissions in today’s process plants.
He opened noting some of the increasing regulatory requirements for reducing greenhouse gas emissions both here in the U.S. and across the globe. For petroleum and chemicals companies increased energy efficiency and reduced emissions is a priority. Process energy usage is the largest controllable cost in most plants.
Doug showed a general process site energy flow diagram:
He shared percentages for how power is consumed for chemical plants and another for refineries.
He highlighted energy saving investment options on a 3×3 grid of potential savings versus time & capital to implement. For example, increased insulation, steam trap monitoring and heat exchanger maintenance are easier to implement and deliver energy savings, but not like constructing a co-generation plant on the site.
Doug showed opportunities for a typical 200,000 barrel per day refinery:
Steam system optimization is challenging due to frequent demand changes demand at different steam pressures. Also, producers and consumers are widely distributed geographically around the refinery and multiple groups have control over their local steam equipment – uncoordinated disturbances. From a process control standpoint, there is a wide range of dynamic responses for manipulated variable changes.
He shared several case studies where the energy savings paid for the work performed within a year.
Doug highlighted some available standards for designing an executing an energy savings program. ISO 50001- Energy management systems –Requirements with guidance for use. A second standard around measurement and verification protocols is ANSI/MSE 50021 – Superior Energy Performance – Additional requirements beyond ISO 50001.
For energy assessments, key considerations include:
- Start with overall site balance – understand major limits and tradeoffs
- Measure and quantify – identify key variables for controllable marginal energy usage (can differ from base usage)
- Prioritize – low hanging fruit and major users
- Clear management focus and responsibility for implementation – but everyone should be involved
- Publish a regular scorecard – “If you don’t keep score you are only practicing”
Doug summarized with three key points:
- Energy is the largest controllable cost in process operation – its efficient production and use are keys to plant profitability. Reducing energy use is the best way to reduce emissions.
- Automation and Advanced Automation are keys to effective use and management of energy and emissions in the plant
- Implementation of a program to save energy and reduce emissions requires a disciplined approach to evaluation and analysis