PTQ Q2 2022 Issue

Continuous operational tuning of refinery fired heaters

Improving the energy efficiency of direct fired heaters represents an enormous potential for sustained energy savings and the reduction of refinery carbon footprint

EULER JIMÉNEZ G Independent Advisor and Instructor on Fired Heaters

P etroleum refineries are high emitters of greenhouse gases (GHG), mainly CO 2 , but also NOx and sometimes CH 4 and SO 2 , from the combustion of fossil fuels. T raditionally, process optimisa - tion strategies have been driven by commercial interests to maximise asset margins and increase busi - ness revenues. In more recent years, increasing public awareness on envi - ronmental and climate issues, as well as specific world events such as the Conference of the Parties held in Paris in 2015 (COP21), organ - ised under the United Nations Framework Convention on Climate Change (UNFCCC), have meant that compliance with environmen - tal regulations and mandates is now a major if not the main considera - tion for refinery optimisation strat - egies. Discussions between national regulatory entities and refinery owners on compliance with envi - ronmental directives have generated wide-ranging plans for reducing the refinery carbon footprint in accord - ance with UNFCCC guidelines. As seen in Table 1 , overall CO 2 emissions from the use of fossil fuels increased over the decade to 32 660 Mt/y in 2019, before a decline of approximately 5% in 2020 (to 31 066 Mt/y) 1 as a consequence of the Covid-19 pandemic. In 2020, oil and gas-related CO 2 emissions amounted to 31% and 25%, respec - tively, for a combined total of approximately 17 086 Mt/y. A review of 1056 oil refineries 2 showed that CO 2 emissions from oil refining amounted to about 1300 Mt in 2018, representing approxi - mately 4% of the overall figure for that year. Authors of the study fore -

tal balance sheet. The notion of generating GHG reduction actions within refinery operations and not just through the suppression of fos - sil fuel usage makes a lot of sense, especially when considering the need for emission reductions in the short term. It would constitute a more reasonable transition strategy rather than having to wait until the time when or if renewable electric - ity becomes available at sufficient scale to meet global energy demand. Such a proactive notion could be extended even further to generate adequate environmental momen - tum on top of and beyond corporate social responsibility (CSR). CO 2 emissions in oil refineries: a joint responsibility within the refinery As major consumers of fossil fuels, direct fired heaters greatly influence the operating costs and economic performance of petroleum refiner - ies. For this reason, improving the energy efficiency of process heaters represents an enormous potential for sustained energy savings and the reduction of refinery carbon footprint. Many refining facilities have heat - ers that operate with lower thermal efficiencies, higher stack emissions, and reduced run cycles compared with their design specifications. A high consumption of fossil fuels in process heaters brings proportional amounts of CO 2 emitted into the atmosphere. Natural draft designs represent a significant share of the refinery heater population. These units operate ‘open to the atmos - phere’, although at a pressure slightly lower than atmospheric

Global CO 2 emissions fromenergy, Mt/y *

2010

2015

2018

2019

2020

29 926 31 703

32 642 32 660 31 066

* 1 Mt = 106 tonnes = 1 billion tonnes (US)

Table 1

cast that if current technical specifi - cations and operational conditions prevail, those refineries will cumu - latively emit 16 500 Mt of CO 2 dur - ing the ongoing decade (2020-2030). Refiners in the EU are now operat - ing within the EU emissions trad - ing scheme, whilst in many other countries, refiners are obliged to include the impact of either an exist - ing or a pending carbon tax on the downstream sector in their forward planning. As major consumers of fossil fuels, direct fired heaters greatly influence the operating costs and economic performance of petroleum refineries A recent article in PTQ 3 found a number of areas fundamental for reducing CO 2 Scope 1 emissions, where process and operations could be optimised with almost no invest - ment. Specifically, energy efficiency represents an opportunity for near- term refinery cost reductions and improvements in the environmen -

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