Energy Management and the Sustainability of the Downstream Industry

Introduction and Context

Nowadays, two actions are inadmissible for environmentally and economically sustainable refineries, steam leaks and hydrogen relief to flare system.

???????????The profitability of a crude oil refinery is directly proportional to his capacity to add value to the processed crude oil, aiming to maximize the production of high added value streams and derivatives. Equation 1 presents a simplified concept of the liquid refining margin.?

The first term in Equation 1 corresponds to the obtained revenue through the commercialization of the crude oil derivatives, represented by the sum of the product between the derivative market value and the volume or weight commercialized. As aforementioned, the profitability or refining margin is directly proportional to the refinery capacity to add value to the processed crude slate, the maximization of higher added value derivatives leads to the maximization of the first term in the Equation 1.?

In Equation 1, the term Pc corresponds to the acquisition cost of the crude oil, the refiners normally don’t have control about the market and the acquisition cost of petroleum that is controlled by the geopolitical scenario and the international market. The cost reduction in the crude oil acquisition can be achieved through the processing of heavier crude oils which have relatively low cost, however, due to the lower distillates yield and higher contaminants content, the processing of heavier crude slates requires refining configurations with higher conversion capacity, raising the operational costs. ?

The fixed and variable costs, (Fc + Vc), represents the operational costs of refiners. Figure 1 shows a simplified scheme to the profitability in the downstream industry, highlighting the refiners cost composition. ?

Figure 1 – Simplified Composition of Profitability for Crude Oil Refineries

???????????Considering that the energy consumption represents over than 60 % of total costs of a typical crude oil refinery, the capacity to optimize and reduce the wastage energy is a key factor in the competitive game in the downstream industry.

Simple and Available Alternatives to Energy Optimization

???????????In a typical crude oil refinery, it’s possible to identify two basic ways to improve profitability through energy optimization:

1 – Consumption Reduction – Normally this way involves a direct impact over the production yield and quality of the derivatives or in the auxiliary processes, so the simple reduction in the energy consumption can be a difficult alternative;

2 – Cost Reduction of the Energy – This way involves actions capable to optimize the energy consumption and minimize the energy wastages through reliability improvement, these actions normally will represent a reduction in the global energy consumption of the refinery.

???????????Among the optimization opportunities it’s required to answer some questions like when it’s advantage to use thermal or electric energy, what is the best operation scenario to change electrical equipment to turbines, what is the best time to maximize the internal power generation in the refinery?

???????????These questions can be answered using adequate simulators considering key information like the natural gas prices, equipment availability and reliability as well as the operating threats of key processing units like FCC.

???????????Among the consolidated techniques to optimize energy consumption we can quote the use of Pinch analysis to reduce the necessity of hot utilities in the processing units as well as maximize the energy recovery from the process. This alternative in especially attractive in crude oil distillation, FCC, and Delayed Coking units due to the amount of energy applied to the processes.

The use of equipment load management systems, speed monitoring for rotating equipment, and thermal efficiency monitoring systems, control and monitoring the flare gas emissions as well as the measure flowrate of gases discharged to flares system can help to identify bad actors and promote effective actions to optimize the power consumption in the process plant.

???????????Some alternatives to reduce the energy need in the crude oil refineries involves some capital investments in revamps or new designs. A widely energy optimization action has been the revamp of fired heaters and furnaces aiming to improve the efficiency and minimize the greenhouse gas emissions.

???????????The crude oil distillation unit is the largest energy consumption in a crude oil refinery and there are many optimization opportunities in this processing unit. Establish an adequate overflash can save great amount of energy in the fired heaters, for processing units with higher processing capacity, the use of preflash configuration can help the refiners to reduce the energy intensity of the downstream steps of the process. Figure 2 presents a crude oil distillation unit relying on preflash column.?

?Figure 2 – Crude Oil Distillation with Preflash Column

???????????An evolution of the preflash configuration is the progressive distillation technology, developed by the Technip Company. This concept, consider that the lighter fractions are superheated in the conventional process leading to an energy wastage, to avoid this effect the progressive distillation concept applies a series of distillation towers focusing to supply only the required energy to promote de desired separation. Figure 3 presents a basic process flow with the concept of progressive distillation.

Figure 3 – The Concept of Progressive Distillation

???????????The separation processes are intensive in the energy consumption and the optimization of the internals of towers and separating vessels can help the refiners to minimize the energy consumption and these actions can be an attractive alternative to revamp of processing units. The use of low pressure drop internals and dividing wall distillation columns are effective actions in this sense.

???????????Optimization and design actions can offer good results, but it’s necessary to ensure the reliability and the availability to the refining hardware before these actions. One of the main issues of the energy system in a crude oil refinery is steam leaks and the recovery of steam condensate, maximize the steam condensate recovery and minimize the steam leaks can be seems obvious but is fundamental and sometimes are underestimated for some refiners. ?Some questions need to be answered as a diagnostic step to reveal the real concern of these questions to a refinery management staff.

1 - Has a specific maintenance program been established for steam traps??What is the frequency of review of that evaluation program?

?2 - How proactive has the refinery personnel been in managing and solving condensate and steam leaks?

3 - What is the response of the refinery for managing compressed air system leaks?

4 - What are the responses if insulation systems are subpar?

?????Another key moment to reach an optimized energy system in a crude oil refinery is the planned shutdown. The participation of process engineers in the planning steps of turnaround of the processing units is fundamental to help the maintenance team to identify and solve inefficiency points as well as it’s fundamental to understand the scenario of the crude oil refinery during the turnaround, which processing units will stop? How we can optimize the operation of the processing units which will keep in operation?

?The Impact of the Energy Management in the Greenhouse Gases Emissions

?????More relevant than the profitability issues related with the energy management of the crude oil refineries is the relation of greenhouse gases emissions. According to data from RITCHIE, 2020 the energy sector is responsible for the major part (Over than 70 %) of the world greenhouse gases emissions and the industrial sector is responsible for over than 24 % of this total, and the crude oil industry is responsible of a significant amount of these emissions. In this sense, to achieve more sustainable operations is essential to control and minimize the carbon emissions in crude oil refineries and this relies on an adequate management energy consumption.

?????According to data from the United States Environmental Protection Agency (EPA, 2010), the combustion processes are responsible for over than 60 % of the CO2 gas emissions in a typical crude oil refinery followed by the burn of catalyst coke in FCC units with 23 % and the hydrogen production plants with close to 6 %, the remain contribution is shared with another processes like derivatives storage, sulfur recovery plants, and flaring systems. This data revels the relevance of to minimize the energy wastage in the refining processes aiming to ensure the sustainability of the refining business. ?Figure 4 Summarizes some available actions capable to minimize the greenhouse gases emissions in the crude oil refineries.

Figure 4 – Available Actions to Minimize Greenhouse Gases Emissions in Crude Oil Refineries.

?????The energy management actions became essential to the sustainability of the crude oil refining players and needs to be an essential part of any strategy in the downstream industry both to environmental impact and economic competitiveness between the players, as presented above, the sustainability of the downstream business is strongly dependent of the adequate energy management of the refining assets.

References

1.????KARATAS, Z. TURKOGLU, S. – A Refinery’s Journey to Energy Efficiency, PTQ Magazine 2016.

2.????RIKHTEGAR, F. SADIGHI, S. – Optimization of Energy Consumption, PTQ Magazine 2015.

3.????CONCAWE. EU Refinery Energy Systems and Efficiency: Conservation of Clean Air and Water in Europe 2012. Available at: https://www.concawe.eu/wp-content/uploads/2017/01/rpt_12-03-2012-01520-01-e.pdf (Acessed on 01 March 2022)

4.????FAWKES, S. Energy Efficiency: The Definitive Guide to the Cheapest, Cleanest, Fastest Source of Energy. 1st edition, Routledge Press, 2013.

5.????KAISER, V. Industrial Energy Management: Refining, Petrochemicals and Gas Processing Techniques. Editions Technip, 1993.

6.????ROSSITER, A.P., JONES, B.P. Energy Management and Efficiency for the Process Industries. 1st edition, Wiley-AIChE Press, 2015.

7.????RITCHIE, H. Sector by Sector: Where do Global Greenhouse Gas Emissions Come From? Our World in Data, 2020. Available at: https://ourworldindata.org/ghg-emissions-by-sector (Accessed on 01 March of 2022).

8.????United States Environmental Protection Agency (EPA). Available and Emerging Technologies for Reducing Greenhouse Gas Emissions from the Petroleum Refining Industry, 2010. Available at: https://www.epa.gov/sites/default/files/2015-12/documents/refineries.pdf?(Accessed on 01 March of 2022).?

Dr. Marcio Wagner da Silva is Process Engineer and Operating Manager on Crude Oil Refining Industry based in S?o José dos Campos, Brazil. Bachelor’s in Chemical Engineering from University of Maringa (UEM), Brazil and PhD. in Chemical Engineering from University of Campinas (UNICAMP), Brazil. Has extensive experience in research, design and construction to oil and gas industry including developing and coordinating projects to operational improvements and debottlenecking to bottom barrel units, moreover Dr. Marcio Wagner have MBA in Project Management from Federal University of Rio de Janeiro (UFRJ), in Digital Transformation at PUC/RS, and is certified in Business from Getulio Vargas Foundation (FGV).