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With the enormous potential for reducing the refinery carbon footprint by increasing direct fired heater efficiency, what successful cases provide an example of increased efficiency and reduced emissions?

Jul-2022

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RUPAM MUKHERJEE, ENGINEERS INDIA LIMITED, rupammukherjee86@gmail.com

We have excellent case studies of retrofitting existing fired heaters with latest design compact air preheaters. This helps in recovering the maximum heat from the outgoing flue gases, thereby maximizing efficiency. This is more important considering that the IRR of these projects over the lifetime lead to significant savings for the end user, with very healthy contribution towards reducing the carbon footprint. Decision to adopt an APH or not has historically been governed by fuel cost economics. However, our studies exemplify that with carbon cost coming into the frame of things quick and fast, tables are overturned. With a reasonable carbon cost, APHs will become very much economically feasible, however, with existing assets, plot can be a major issue.

Apart from above, operational adjustments are always the lowest hanging fruits. It is often ignored, however, the results can surprise. We have our EngRT digital platform for fired heaters which evaluate the furnace's operation and recommend the best possible scenario with possible adjustments. It also highlights the heat recovery potential and helps in making informed decision. The digital platform can act as on-the-go fired heat auditing tool for keeping the furnaces operating at the maximum efficiency point.

Jun-2023
Brian Burgio, KBC Advanced Technologies, brian.burgio@kbcat.com

Yokogawa has successfully applied our CombustionONE suite to optimize combustion and heat transfer in the fired heater radiant section. We do this by first improving the measurement accuracy, precision, and responsiveness of the pre-combustion components and the post-combustion gases. Once integrated into closed loop control, we have dozens of proven CombustionONE implementations able to SAFELY run much tighter O2 levels that anticipate rather than respond to dynamics in the combustion environment (variable LHV, inconsistent tramp air, swinging air flow, etc). Ultimately, our CombustionONE clients see quantifiable improvements in specific fuel consumption and/or fired asset production, emissions reduction (CO, CO2, NOx), asset integrity (particularly tube and catalyst life), and SAFETY.

Aug-2022
Afshin Bakhtiari, Naftoon Arya Eng. Co,, bakhtiari_af@yahoo.com

I have no idea what kind of emission (NOx, SOx or CO) you are talking about. As you know these are competing emissions and in many cases, corrective action for NOx and CO is opposite.

In case of NOx:

1: Using APH for improving the efficiency, would definitely increase NOx production due to increasing combustion air temperature. Considering LNB burners may be useful if you haven’t already used it.
2: Expanding heat transfer area in Firebox and/or Convection Section (Changing Bare tubes with Finned or Studded tubes) can increase efficiency and if the Firebox temperature drops, NOx concentration would decrease.
3: Based on my experience, decreasing Tramp Air by means of leakage prevention and also adjusting Burner Register and Stack Damper on a regular basis, will increase the heater efficiency while NOx will be decreased due to reduction of O2 concentration.
4: If the produced NOx is Fuel-type NOx, changing the fuel from oil to gas would result in a significant reduction of it in any efficiency increasing scenario. Also installation of SCR system might be helpful after appropriate feasibility study.

Aug-2022
Marina Silva, Integrated Global Services, marina.silva@integratedglobal.com

Improving the efficiency of the Radiant and/or Convection section of the fired heater leads to a decrease in fuel consumption (unless a capacity increase was the original objective). A decrease in fuel consumption translates into lower CO2 and NOx emissions.

The radiant section efficiency can be improved with the use of high-emissivity Cetek ceramic coatings applied to the refractory and in case of some heaters (CCR for e.g.) to the process tubes. It is important to get the coating vendor to perform a technical evaluation to determine exactly what the % efficiency increase will be and estimate fuel savings, emissions reduction and capacity increase.

Examples:
* Tupras refinery have published a detailed report of a Cetek application in their refinery in a PTQ supplement, Gas 2022.
* Primary Reformer, 21% less NOx, 3.5% less CO2
* CRU, fuel savings and capacity increase
* 4% Emissions Reduction in ammonia reformer
The convection section efficiency can be improved with the use of convection section cleaning. A Tube Tech solution utilizes robotic cleaning that achieves a 90%+ clean area with no risks associated with manual/man entry cleaning.

Examples:
* Tupras refinery published a detailed report of a Tube Tech application in their refinery in the PTQ 2020.
* Cracking Furnace, convection section fouling removed
* Energy and CO2 savings achieved
* Substantial Fuel and CO2 savings in a German refinery

Jul-2022
HervÃ© Lavieu, Heurtey Petrochem Solutions, herve.lavieu@heurtey.net

To increase the fuel efficiency of existing heaters, several options can be considered depending on the inlet temperature of the process fluid and the temperature of the flue gas rejected to the atmosphere.

The first solution is revamping the heater to increase the heat exchange surface of the coil; this solution has been implemented on natural draft heaters and does not require the installation of additional equipment such as air and flue gas fans.

The second option consists of the installation of an air preheating system (APH) to preheat the combustion air by recovery of heat on the flue gas going to the stack. And when the heater is already equipped with such an APH, the installation of a new generation APH allows the recovery of more heat from the flue gas. In this situation, we have installed an APH with an enhanced exchange surface but also utilising special coated or polymer-based tubes, operating below the acid dew point (ADP) to reach low stack temperatures (<90°C/195°F).

Jul-2022
Ron Beck, AspenTech, ron.beck@aspentech.com

For most refineries and bulk chemical sites, the opportunity is there to improve energy efficiency by 10-30%, with a significant amount of that through optimisation of operations. A recent benchmark of European refineries shows that they lag significantly behind best-in-class global refiners in energy efficiency. Some examples of how digital solutions are achieving energy efficiencies and reduced carbon emissions include:
- KNPC identifies opportunities across the refinery to save 57,890 tpy of CO2 and reach an EII rating of 3.2 without significant investment through rigorous modelling of energy supply and demand in Aspen Performance engineering. Additionally, it identified opportunities with added CAPEX that allowed it to save 260 MBTU/hr with an EII of 6
- Sinopec decreased by 13% the total fuel gas to unit feed ratio using APC (Aspen DMC3) at an integrated refining petrochemical complex
- An international bulk chemicals producer reduced its fuel gas consumption by 1.7 to 4.3 kg/hr per day per furnace in less than a month using multivariate statistical analysis with Aspen ProMV
- Tupras reduced fuel consumption by 20% through heat integration and higher energy recovery
- Probably the broadest existing case study is the 10% carbon reduction Dow Chemical has reported to the investor community over the past 10 years through the combined use of APC and digital twin models online, both using AspenTech technology.

Jul-2022